path: root/net-print/hplip/files/hplip-3.11.12-fast-pp.patch

Speed up HPLIP's parallel port I/O

HPLIP should stop emulating IEE1284 ECP in userspace; that requires so many
ioctls that it's uncomfortably (and sometimes unusably) slow, even on fast
systems.  Instead, it should use ppdev read/write calls, working around ppdev
quirks/bugs as necessary.

Until now, we avoided this because we feared that using ppdev would make us
susceptible to variations in PC parallel port hardware.  However, it turns out
that the kernel already addresses that problem: on PCs, the kernel defaults to
software-emulated ECP, which is exactly what the current HPLIP code does.
Using the kernel code avoids the massive ioctl overhead, and it makes it
possible to use hardware-accelerated ECP in those cases where it works.

To apply this patch, 'cd' into the unpacked hplip source directory and run:
$ patch -p1 <../hplip-fast-pp-v2.patch
$ libtoolize --force
$ AUTOMAKE="automake --foreign" autoreconf
(Remember to use the --enable-pp-build option with ./configure)

Patch by Daniel Gnoutcheff <daniel@gnoutcheff.name>
Thanks to Daniel Pielmeir for figuring out the autotools bits

diff -ur hplip-3.12.2/configure.in hplip-3.12.2-fast-pp/configure.in
--- hplip-3.12.2/configure.in	2012-02-01 06:56:29.000000000 -0500
+++ hplip-3.12.2-fast-pp/configure.in	2012-02-20 21:09:45.850744922 -0500
@@ -222,6 +222,7 @@
 else
    AC_MSG_RESULT(no)
 fi
+AM_CONDITIONAL(PP_BUILD, test x$pp_build = xyes)
    
 AC_MSG_CHECKING([for scanner build])
 AC_ARG_ENABLE(scan_build,
diff -ur hplip-3.12.2/io/hpmud/pp.c hplip-3.12.2-fast-pp/io/hpmud/pp.c
--- hplip-3.12.2/io/hpmud/pp.c	2012-02-01 06:53:52.000000000 -0500
+++ hplip-3.12.2-fast-pp/io/hpmud/pp.c	2012-02-20 19:28:27.990747569 -0500
@@ -28,6 +28,8 @@
 
 #include "hpmud.h"
 #include "hpmudi.h"
+#include <signal.h>
+#include <time.h>
 
 mud_device_vf __attribute__ ((visibility ("hidden"))) pp_mud_device_vf = 
 {
@@ -67,17 +69,6 @@
    .channel_read = musb_dot4_channel_read
 };
 
-static int frob_control(int fd, unsigned char mask, unsigned char val)
-{
-   struct ppdev_frob_struct frob;
-
-   /* Convert ieee1284 control values to PC-style (invert Strobe, AutoFd and Select) . */
-   frob.val = val ^ (mask & (PARPORT_CONTROL_STROBE | PARPORT_CONTROL_AUTOFD | PARPORT_CONTROL_SELECT));
-
-   frob.mask = mask;
-   return ioctl(fd, PPFCONTROL, &frob);
-}
-
 static unsigned char read_status(int fd)
 {
    unsigned char status;
@@ -88,493 +79,6 @@
    return (status ^ PARPORT_STATUS_BUSY); 
 } 
 
-static int wait_status(int fd, unsigned char mask, unsigned char val, int usec)
-{
-   struct timeval tmo, now;
-   struct timespec min;
-   unsigned char status;
-   int cnt=0;
-   
-   gettimeofday (&tmo, NULL);
-   tmo.tv_usec += usec;
-   tmo.tv_sec += tmo.tv_usec / 1000000;
-   tmo.tv_usec %= 1000000;
-
-   min.tv_sec = 0;
-   min.tv_nsec = 5000000;  /* 5ms */
-
-   while (1)
-   {
-      status = read_status(fd);
-      if ((status & mask) == val)
-      {
-	//         bug("found status=%x mask=%x val=%x cnt=%d: %s %d\n", status, mask, val, cnt, __FILE__, __LINE__);
-         return 0;
-      } 
-      cnt++;
-      //      nanosleep(&min, NULL);
-      gettimeofday(&now, NULL);
-      if ((now.tv_sec > tmo.tv_sec) || (now.tv_sec == tmo.tv_sec && now.tv_usec > tmo.tv_usec))
-      {
-         DBG("wait_status timeout status=%x mask=%x val=%x us=%d\n", status, mask, val, usec);
-         return -1;   /* timeout */
-      }
-   }
-}
-
-static int wait(int usec)
-{
-   struct timeval tmo, now;
-   int cnt=0;
-   
-   gettimeofday (&tmo, NULL);
-   tmo.tv_usec += usec;
-   tmo.tv_sec += tmo.tv_usec / 1000000;
-   tmo.tv_usec %= 1000000;
-
-   while (1)
-   {
-      cnt++;
-      gettimeofday(&now, NULL);
-      if ((now.tv_sec > tmo.tv_sec) || (now.tv_sec == tmo.tv_sec && now.tv_usec > tmo.tv_usec))
-      {
-         return 0;   /* timeout */
-      }
-   }
-}
-
-static int ecp_is_fwd(int fd)
-{
-   unsigned char status;
-
-   status = read_status(fd);
-   if ((status & PARPORT_STATUS_PAPEROUT) == PARPORT_STATUS_PAPEROUT)
-      return 1;
-   return 0;
-}
-
-static int ecp_is_rev(int fd)
-{
-   unsigned char status;
-
-   status = read_status(fd);
-   if ((status & PARPORT_STATUS_PAPEROUT) == 0)
-      return 1;
-   return 0;
-}
-
-static int ecp_rev_to_fwd(int fd)
-{
-   int dir=0;
-
-   if (ecp_is_fwd(fd))
-      return 0;
-
-   /* Event 47: write NReverseRequest/nInit=1 */
-   frob_control(fd, PARPORT_CONTROL_INIT, PARPORT_CONTROL_INIT);
-
-   /* Event 48: wait PeriphClk/nAck=1, PeriphAck/Busy=0 */
-   //   wait_status(fd, PARPORT_STATUS_PAPEROUT | PARPORT_STATUS_BUSY, PARPORT_STATUS_PAPEROUT, SIGNAL_TIMEOUT);
-
-   /* Event 49: wait nAckReverse/PError=1 */
-   wait_status(fd, PARPORT_STATUS_PAPEROUT, PARPORT_STATUS_PAPEROUT, PP_SIGNAL_TIMEOUT);
-
-   ioctl(fd, PPDATADIR, &dir);
-
-   return 0;
-}
-
-static int ecp_fwd_to_rev(int fd)
-{
-   int dir=1;
-
-   if (ecp_is_rev(fd))
-      return 0;
-
-   /* Event 33: NPeriphRequest/nFault=0, PeriphAck/Busy=0 */
-   wait_status(fd, PARPORT_STATUS_BUSY | PARPORT_STATUS_ERROR, 0, PP_DEVICE_TIMEOUT);
-
-   /* Event 38: write HostAck/nAutoFd=0 */
-   ioctl(fd, PPDATADIR, &dir);
-   frob_control(fd, PARPORT_CONTROL_AUTOFD, 0);
-   wait(PP_SETUP_TIMEOUT);
-   
-   /* Event 39: write NReverseRequest/nInit=0 (start bus reversal) */
-   frob_control(fd, PARPORT_CONTROL_INIT, 0);
-
-   /* Event 40: wait nAckReverse/PError=0 */
-   wait_status(fd, PARPORT_STATUS_PAPEROUT, 0, PP_SIGNAL_TIMEOUT);
-
-   return 0;
-}
-
-static int ecp_write_addr(int fd, unsigned char data)
-{
-   int cnt=0, len=0;
-   unsigned d=(data | 0x80); /* set channel address bit */
-
-   ecp_rev_to_fwd(fd);
-
-   /* Event 33: PeriphAck/Busy=0 */
-   if (wait_status(fd, PARPORT_STATUS_BUSY, 0, PP_SIGNAL_TIMEOUT))
-   {
-      BUG("ecp_write_addr transfer stalled\n"); 
-      goto bugout;
-   }
-
-   while (1)
-   {   
-      /* Event 34: write HostAck/nAutoFD=0 (channel command), data */
-      frob_control(fd, PARPORT_CONTROL_AUTOFD, 0);
-      ioctl(fd, PPWDATA, &d);
-
-      /* Event 35: write HostClk/NStrobe=0 */
-      frob_control(fd, PARPORT_CONTROL_STROBE, 0);
-
-      /* Event 36: wait PeriphAck/Busy=1 */
-      if (wait_status(fd, PARPORT_STATUS_BUSY, PARPORT_STATUS_BUSY, PP_SIGNAL_TIMEOUT))
-      {
-
-         /* Event 72: write NReverseRequest/nInit=0 (Host Transfer Recovery) */
-         frob_control(fd, PARPORT_CONTROL_INIT, 0);
-
-         /* Event 73: wait nAckReverse/PError=0 */
-         wait_status(fd, PARPORT_STATUS_PAPEROUT, 0, PP_SIGNAL_TIMEOUT);
-
-         /* Event 74: write NReverseRequest/nInit=1 */
-         frob_control(fd, PARPORT_CONTROL_INIT, PARPORT_CONTROL_INIT);
-
-         /* Event 75: wait nAckReverse/PError=1 */
-         wait_status(fd, PARPORT_STATUS_PAPEROUT, PARPORT_STATUS_PAPEROUT, PP_SIGNAL_TIMEOUT);
-
-         cnt++;
-         if (cnt > 4)
-         {
-            BUG("ecp_write_addr transfer stalled\n"); 
-            goto bugout;
-         }
-         BUG("ecp_write_addr host transfer recovery cnt=%d\n", cnt); 
-         continue;  /* retry */
-      }
-      break;  /* done */
-   } /* while (1) */
-
-   len = 1;
-      
-bugout:
-
-   /* Event 37: write HostClk/NStrobe=1 */
-   frob_control(fd, PARPORT_CONTROL_STROBE, PARPORT_CONTROL_STROBE);
-
-   return len;
-}
-
-static int ecp_write_data(int fd, unsigned char data)
-{
-   int cnt=0, len=0;
-
-   //   ecp_rev_to_fwd(fd);
-
-   /* Event 33: check PeriphAck/Busy=0 */
-   if (wait_status(fd, PARPORT_STATUS_BUSY, 0, PP_SIGNAL_TIMEOUT))
-   {
-      BUG("ecp_write_data transfer stalled\n"); 
-      goto bugout;
-   }
-
-   while (1)
-   {   
-      /* Event 34: write HostAck/nAutoFD=1 (channel data), data */
-      frob_control(fd, PARPORT_CONTROL_AUTOFD, PARPORT_CONTROL_AUTOFD);
-      ioctl(fd, PPWDATA, &data);
-
-      /* Event 35: write HostClk/NStrobe=0 */
-      frob_control(fd, PARPORT_CONTROL_STROBE, 0);
-
-      /* Event 36: wait PeriphAck/Busy=1 */
-      if (wait_status(fd, PARPORT_STATUS_BUSY, PARPORT_STATUS_BUSY, PP_SIGNAL_TIMEOUT))
-      {
-
-         /* Event 72: write NReverseRequest/nInit=0 (Host Transfer Recovery) */
-         frob_control(fd, PARPORT_CONTROL_INIT, 0);
-
-         /* Event 73: wait nAckReverse/PError=0 */
-         wait_status(fd, PARPORT_STATUS_PAPEROUT, 0, PP_SIGNAL_TIMEOUT);
-
-         /* Event 74: write NReverseRequest/nInit=1 */
-         frob_control(fd, PARPORT_CONTROL_INIT, PARPORT_CONTROL_INIT);
-
-         /* Event 75: wait nAckReverse/PError=1 */
-         wait_status(fd, PARPORT_STATUS_PAPEROUT, PARPORT_STATUS_PAPEROUT, PP_SIGNAL_TIMEOUT);
-
-         cnt++;
-         if (cnt > 4)
-         {
-            BUG("ecp_write_data transfer stalled\n"); 
-            goto bugout;
-         }
-         BUG("ecp_write_data host transfer recovery cnt=%d\n", cnt); 
-         continue;  /* retry */
-      }
-      break;  /* done */
-   } /* while (1) */
-
-   len = 1;
-      
-bugout:
-
-   /* Event 37: write HostClk/NStrobe=1 */
-   frob_control(fd, PARPORT_CONTROL_STROBE, PARPORT_CONTROL_STROBE);
-
-   return len;
-}
-
-static int ecp_read_data(int fd, unsigned char *data)
-{
-   int len=0;
-
-   //   ecp_fwd_to_rev(fd);
-
-   /* Event 43: wait PeriphClk/NAck=0 */
-   if (wait_status(fd, PARPORT_STATUS_ACK, 0, PP_SIGNAL_TIMEOUT))
-   {
-      len = -1;
-      goto bugout;
-   }
-   ioctl(fd, PPRDATA, data);
-
-   /* Event 44: write HostAck/nAutoFd=1 */
-   frob_control(fd, PARPORT_CONTROL_AUTOFD, PARPORT_CONTROL_AUTOFD);
-
-   /* Event 45: wait PeriphClk/NAck=1 */
-   wait_status(fd, PARPORT_STATUS_ACK, PARPORT_STATUS_ACK, PP_SIGNAL_TIMEOUT);
-
-   /* Event 46: write HostAck/nAutoFd=0 */
-   frob_control(fd, PARPORT_CONTROL_AUTOFD, 0);
-
-   len = 1;
-      
-bugout:
-
-   return len;
-}
-
-static int ecp_read(int fd, void *buffer, int size, int usec)
-{
-   int i=0;
-   unsigned char *p = (unsigned char *)buffer;
-   
-   ecp_fwd_to_rev(fd);
-
-   while (i < size)
-   {
-      if (ecp_read_data(fd, p+i) != 1)
-      {
-         usec-=PP_SIGNAL_TIMEOUT;
-         if (usec > 0)
-            continue;
-
-//         return -1;
-         return -ETIMEDOUT;   /* timeout */
-      }
-      i++;
-   }
-   return i;
-}
-
-static int ecp_write(int fd, const void *buffer, int size)
-{
-   int i;
-   unsigned char *p = (unsigned char *)buffer;
-   static int timeout=0;
-
-   if (timeout)
-   {
-      timeout=0;
-      return -1;        /* report timeout */
-   }
-   
-   ecp_rev_to_fwd(fd);
-
-   for (i=0; i < size; i++)
-   {
-      if (ecp_write_data(fd, p[i]) != 1)
-      {
-         if (i)
-            timeout=1;  /* save timeout, report bytes written */
-         else
-            i=-1;       /* report timeout */
-         break;
-      }
-   }
-   return i;
-}
-
-static int nibble_read_data(int fd, unsigned char *data)
-{
-   int len=0;
-   unsigned char nibble;   
-
-   /* Event 7: write HostBusy/nAutoFd=0 */
-   frob_control(fd, PARPORT_CONTROL_AUTOFD, 0);
-
-   /* Event 8: peripheral sets low-order nibble. */
-
-   /* Event 9: wait PtrClk/NAck=0 */
-   if (wait_status(fd, PARPORT_STATUS_ACK, 0, PP_SIGNAL_TIMEOUT))
-   {
-      len = -1;
-      goto bugout;
-   }
-   nibble = read_status(fd) >> 3;
-   nibble = ((nibble & 0x10) >> 1) | (nibble & 0x7);
-   *data = nibble;
-
-   /* Event 10: write HostBusy/nAutoFd=1 */
-   frob_control(fd, PARPORT_CONTROL_AUTOFD, PARPORT_CONTROL_AUTOFD);
-
-   /* Event 11: wait PtrClk/NAck=1 */
-   wait_status(fd, PARPORT_STATUS_ACK, PARPORT_STATUS_ACK, PP_SIGNAL_TIMEOUT);
-
-   /* Event 7: write HostBusy/nAutoFd=0 */
-   frob_control(fd, PARPORT_CONTROL_AUTOFD, 0);
-
-   /* Event 8: peripheral sets high-order nibble. */
-
-   /* Event 9: wait PtrClk/NAck=0 */
-   if (wait_status(fd, PARPORT_STATUS_ACK, 0, PP_SIGNAL_TIMEOUT))
-   {
-      len = -1;
-      goto bugout;
-   }
-   nibble = read_status(fd) >> 3;
-   nibble = ((nibble & 0x10) >> 1) | (nibble & 0x7);
-   *data |= (nibble<<4);
-
-   /* Event 10: write HostBusy/nAutoFd=1 */
-   frob_control(fd, PARPORT_CONTROL_AUTOFD, PARPORT_CONTROL_AUTOFD);
-
-   /* Event 11: wait PtrClk/NAck=1 */
-   wait_status(fd, PARPORT_STATUS_ACK, PARPORT_STATUS_ACK, PP_SIGNAL_TIMEOUT);
-
-   len = 1;
-      
-bugout:
-
-   return len;
-}
-
-static int nibble_read(int fd, int flag, void *buffer, int size, int usec)
-{
-   int i=0;
-   unsigned char *p = (unsigned char *)buffer;
-   int m = IEEE1284_MODE_NIBBLE | flag;
-   int mc = IEEE1284_MODE_COMPAT;
-   unsigned char status;
-
-   ioctl (fd, PPNEGOT, &mc);
-   if (ioctl (fd, PPNEGOT, &m))
-   {
-      DBG("nibble_read negotiation failed: %m\n");
-      return -1;
-   }
-
-   while (i < size)
-   {
-      if (nibble_read_data(fd, p+i) != 1)
-      {
-         usec-=PP_SIGNAL_TIMEOUT;
-         if (usec > 0)
-            continue;
-
-//         return -1;
-         return -ETIMEDOUT;   /* timeout */
-      }
-
-      i++;
-
-      /* More data? */
-      status = read_status(fd);
-      if (status & PARPORT_STATUS_ERROR)
-      {
-         /* Event 7: write HostBusy/nAutoFd=0, idle phase */
-         frob_control(fd, PARPORT_CONTROL_AUTOFD, 0);
-         
-         break;  /* done */
-      }
-   }
-
-   return i;
-}
-
-static int compat_write_data(int fd, unsigned char data)
-{
-   int len=0;
-
-   /* wait Busy=0 */
-   if (wait_status(fd, PARPORT_STATUS_BUSY, 0, PP_DEVICE_TIMEOUT))
-   {
-      BUG("compat_write_data transfer stalled\n"); 
-      goto bugout;
-   }
-
-   ioctl(fd, PPWDATA, &data);
-   wait(PP_SETUP_TIMEOUT);
-
-   /* write NStrobe=0 */
-   frob_control(fd, PARPORT_CONTROL_STROBE, 0);
-
-   /* wait Busy=1 */
-   if (wait_status(fd, PARPORT_STATUS_BUSY, PARPORT_STATUS_BUSY, PP_SIGNAL_TIMEOUT))
-   {
-      BUG("compat_write_data transfer stalled\n"); 
-      goto bugout;
-   }
-
-   /* write nStrobe=1 */
-   frob_control(fd, PARPORT_CONTROL_STROBE, PARPORT_CONTROL_STROBE);
-
-   len = 1;
-      
-bugout:
-   return len;
-}
-
-static int compat_write(int fd, const void *buffer, int size)
-{
-   int i=0;
-   unsigned char *p = (unsigned char *)buffer;
-   int m = IEEE1284_MODE_COMPAT;
-   static int timeout=0;
-
-   if (timeout)
-   {
-      timeout=0;
-      return -1;        /* report timeout */
-   }
-
-   if (ioctl(fd, PPNEGOT, &m))
-   {
-      BUG("compat_write failed: %m\n");
-      goto bugout;
-   }
-
-   for (i=0; i < size; i++)
-   {
-      if (compat_write_data(fd, p[i]) != 1)
-      {
-         if (i)
-            timeout=1;  /* save timeout, report bytes written */
-         else
-            i=-1;       /* report timeout */
-         break;
-      }
-   }
-
-bugout:
-   return i;
-}
-
 static int claim_pp(int fd)
 {
    int stat=1;
@@ -617,11 +121,23 @@
 
 static int device_id(int fd, char *buffer, int size)
 {
-   int len=0, maxSize;
+   int len=0, maxSize, mode;
 
    maxSize = (size > 1024) ? 1024 : size;   /* RH8 has a size limit for device id */
 
-   len = nibble_read(fd, IEEE1284_DEVICEID, buffer, maxSize, 0);
+   /* reset (in case someone else stopped in the middle of reading the device
+    * ID) */
+   mode = IEEE1284_MODE_COMPAT;
+   ioctl(fd, PPNEGOT, &mode);
+
+   mode = IEEE1284_MODE_NIBBLE | IEEE1284_DEVICEID;
+   ioctl(fd, PPNEGOT, &mode);
+   len = read(fd, buffer, maxSize);
+
+   /* Reset (for safety) */
+   mode = IEEE1284_MODE_COMPAT;
+   ioctl(fd, PPNEGOT, &mode);
+
    if (len < 0)
    {
       BUG("unable to read device-id ret=%d\n", len);
@@ -720,24 +236,134 @@
    return 0;
 }
 
+static int ecp_write_addr(int fd, unsigned char addr)
+{
+   /* Currently, PPSETMODE always resets the kernel's idea of the current phase
+    * to equal that of the inital phase of the given mode (i.e.
+    * IEEE1284_PH_FWD_IDLE for ECP).  However, we're not actually changing the
+    * mode, we're just modifying the "send command bytes" flag; thus, we do
+    * *not* want the phase to change.  We workaround the kernel's bad behavor by
+    * forcibly refreshing its phase setting whenever we call PPSETMODE.
+    */ 
+   int mode, phase, cmdmode, len, retval;
+
+   /* To send an address, we send an ECP command byte with the high bit set
+    * and the address in the other 7 bits. */
+   unsigned char command = addr | 0x80;
+
+   /* Enable command mode */
+   ioctl(fd, PPGETMODE, &mode);
+   cmdmode = mode | IEEE1284_ADDR;
+   ioctl(fd, PPGETPHASE, &phase);
+   ioctl(fd, PPSETMODE, &cmdmode);
+   ioctl(fd, PPSETPHASE, &phase);
+
+   len = write(fd, &command, 1);
+
+   /* Restore original mode */
+   ioctl(fd, PPGETPHASE, &phase);
+   ioctl(fd, PPSETMODE, &mode);
+   ioctl(fd, PPSETPHASE, &phase);
+
+   if (len == 1)
+      retval = len;
+   else
+   {
+      BUG("ecp_write_addr transfer failed\n");
+      retval = -errno;
+   } 
+
+   return retval; 
+}
+
+static void setup_timeout(int timeout_usec, timer_t *timeout_timer)
+{ 
+   struct sigevent timeout_sigevent = 
+   {
+      .sigev_notify = SIGEV_NONE
+   };
+   struct itimerspec timeout = 
+   {
+      .it_value = 
+      {
+         .tv_sec = timeout_usec / 1000000,
+         .tv_nsec = (timeout_usec % 1000000) * 1000
+      },
+      .it_interval = 
+      {
+         .tv_sec = 0,
+         .tv_nsec = 0
+      }
+   };
+
+   timer_create(CLOCK_MONOTONIC, &timeout_sigevent, timeout_timer);
+   timer_settime(*timeout_timer, 0, &timeout, NULL);
+}
+
+static int timeout_not_expired(timer_t *timer)
+{
+   struct itimerspec timeout;
+   timer_gettime(*timer, &timeout);
+   return timeout.it_value.tv_sec > 0 || timeout.it_value.tv_nsec > 0;
+}
+
+enum io_operation
+{
+   IO_READ,
+   IO_WRITE
+};
+
+static int ppdev_io_with_timeout(enum io_operation operation, 
+      int fd, void *buf, int buf_size, int timeout_usec)
+{ 
+   /* As of Linux 2.6.39, ppdev's read and write implementations do not honor
+    * the timeout values given by PPSETTIME ioctls.  Furthermore, when using
+    * blocking IO, ppdev reads and writes will block forever until at least one
+    * byte is transfered, which is a problem if, say, the peripheral has lost
+    * power and will never respond.  To avoid these issues, we use non-blocking
+    * IO and we implement the timeout ourselves. */
+
+   int offset = 0, retval = 0, error = 0;
+   timer_t timeout_timer;
+
+   setup_timeout(timeout_usec, &timeout_timer);
+   
+   do {
+      switch (operation)
+      {
+         case IO_READ:
+            retval = read(fd, buf + offset, buf_size - offset);
+            break;
+         case IO_WRITE:
+            retval = write(fd, buf + offset, buf_size - offset);
+            break;
+      }
+
+      if (retval >= 0)
+         offset += retval;
+      else if (errno != EAGAIN)
+         error = errno;
+   } while (!error && offset < buf_size && timeout_not_expired(&timeout_timer));
+
+   timer_delete(timeout_timer);
+
+   if (error)
+      return -error;
+   else if (offset == 0)
+      return -ETIMEDOUT;
+   else
+      return offset;
+}
+
 /*********************************************************************************************************************************
  * Parallel port mud_device functions.
  */
 
 int __attribute__ ((visibility ("hidden"))) pp_write(int fd, const void *buf, int size, int usec)
 {
-   int len=0, m;
+   int len;
 
-   ioctl(fd, PPGETMODE, &m);
-
-   if (m & (IEEE1284_MODE_ECPSWE | IEEE1284_MODE_ECP))
-   {
-      len = ecp_write(fd, buf, size);
-   }
-   else
-   {  
-      len = compat_write(fd, buf, size);
-   }
+   len = ppdev_io_with_timeout(IO_WRITE, fd, (void *)buf, size, usec);
 
    DBG("write fd=%d len=%d size=%d\n", fd, len, size);
    DBG_DUMP(buf, len < 32 ? len : 32);
@@ -747,19 +373,9 @@
 
 int __attribute__ ((visibility ("hidden"))) pp_read(int fd, void *buf, int size, int usec)
 {
-   int len=0, m;
-//   int sec = usec/1000000;
-
-   ioctl(fd, PPGETMODE, &m);
+   int len;
 
-   if (m & (IEEE1284_MODE_ECPSWE | IEEE1284_MODE_ECP))
-   {  
-      len = ecp_read(fd, buf, size, usec);
-   }
-   else
-   {
-      len = nibble_read(fd, 0, buf, size, usec);
-   }
+   len = ppdev_io_with_timeout(IO_READ, fd, buf, size, usec);
 
    DBG("read fd=%d len=%d size=%d usec=%d\n", fd, len, size, usec);
    DBG_DUMP(buf, len < 32 ? len : 32);
@@ -779,9 +395,11 @@
 
    if (pd->id[0] == 0)
    {
-      /* First client, open actual kernal device, use blocking i/o. */
+      /* First client, open actual kernal device, use non-blocking i/o. See
+       * comment in ppdev_io_with_timeout() for why we use non-blocking i/o.
+       */
       hpmud_get_uri_datalink(pd->uri, dev, sizeof(dev));
-      if ((fd = open(dev, O_RDWR | O_NOCTTY)) < 0)            
+      if ((fd = open(dev, O_RDWR | O_NOCTTY | O_NONBLOCK)) < 0)            
       {
          BUG("unable to open %s: %m\n", pd->uri);
          goto bugout;
@@ -1037,7 +655,7 @@
          goto bugout;
 
       /* Negotiate ECP mode. */
-      m = IEEE1284_MODE_ECPSWE;
+      m = IEEE1284_MODE_ECP;
       if (ioctl(pd->open_fd, PPNEGOT, &m)) 
       {
          BUG("unable to negotiate %s ECP mode: %m\n", pd->uri);
@@ -1046,7 +664,7 @@
 
       /* Enable MLC mode with ECP channel-77. */
       ecp_write_addr(pd->open_fd, 78);
-      ecp_write(pd->open_fd, "\0", 1);
+      write(pd->open_fd, "\0", 1);
       ecp_write_addr(pd->open_fd, 77);
 
       /* MLC initialize */
@@ -1099,7 +717,7 @@
       pd->mlc_up=0;
 
       ecp_write_addr(pd->mlc_fd, 78);     /* disable MLC mode with ECP channel-78 */
-      ecp_write(pd->mlc_fd, "\0", 1);
+      write(pd->mlc_fd, "\0", 1);
 
       m = IEEE1284_MODE_NIBBLE;
       ioctl(pd->mlc_fd, PPNEGOT, &m);
@@ -1129,7 +747,7 @@
          goto bugout;
 
       /* Negotiate ECP mode. */
-      m = IEEE1284_MODE_ECPSWE;
+      m = IEEE1284_MODE_ECP;
       if (ioctl(pd->open_fd, PPNEGOT, &m)) 
       {
          BUG("unable to negotiate %s ECP mode: %m\n", pd->uri);
@@ -1138,7 +756,7 @@
 
       /* Enable MLC mode with ECP channel-77. */
       ecp_write_addr(pd->open_fd, 78);
-      ecp_write(pd->open_fd, "\0", 1);
+      write(pd->open_fd, "\0", 1);
       ecp_write_addr(pd->open_fd, 77);
 
       /* DOT4 initialize */
@@ -1191,7 +809,7 @@
       pd->mlc_up=0;
 
       ecp_write_addr(pd->mlc_fd, 78);     /* disable MLC mode with ECP channel-78 */
-      ecp_write(pd->mlc_fd, "\0", 1);
+      write(pd->mlc_fd, "\0", 1);
 
       m = IEEE1284_MODE_NIBBLE;
       ioctl(pd->mlc_fd, PPNEGOT, &m);
diff -ur hplip-3.12.2/io/hpmud/pp.h hplip-3.12.2-fast-pp/io/hpmud/pp.h
--- hplip-3.12.2/io/hpmud/pp.h	2012-02-01 06:53:52.000000000 -0500
+++ hplip-3.12.2-fast-pp/io/hpmud/pp.h	2012-02-20 19:28:27.990747569 -0500
@@ -60,18 +60,11 @@
  *   0 - Strobe *
  * 
  *              * inverted
- *
- * Notes:
- *   For ECP mode use low-level parport ioctl instead of high-level parport read/writes because its more reliable. High-level support
- *   for Compatible and Nibble modes are probably ok, but for consistency low-level parport ioctl is used.
- *
  */
 
-#define PP_DEVICE_TIMEOUT 30000000   /* device timeout (us) */
 //#define PP_SIGNAL_TIMEOUT 1000000   /* signal timeout (us), too long for 1ms timeout, DES 8/18/08  */
 //#define PP_SIGNAL_TIMEOUT 1000   /* signal timeout (us), too short for DJ540, DES 8/18/08 */  
 #define PP_SIGNAL_TIMEOUT 100000   /* signal timeout (us), DES 8/18/08 */
-#define PP_SETUP_TIMEOUT 10   /* setup timeout (us) */
 
 struct _mud_device;
 struct _mud_channel;
diff -ur hplip-3.12.2/Makefile.am hplip-3.12.2-fast-pp/Makefile.am
--- hplip-3.12.2/Makefile.am	2012-02-01 06:53:57.000000000 -0500
+++ hplip-3.12.2-fast-pp/Makefile.am	2012-02-20 21:26:21.210745149 -0500
@@ -73,6 +73,9 @@
 libhpmud_la_LDFLAGS = -version-info 0:6:0 -lusb -lpthread
 endif
 libhpmud_la_CFLAGS = -DMUDNAME=\"$(MUDNAME)\" -DCONFDIR=\"$(hplip_confdir)\"
+if PP_BUILD
+libhpmud_la_LDFLAGS += -lrt
+endif
 
 # ip library
 lib_LTLIBRARIES += libhpip.la