V4L/DVB (8914): cx18: Throttle mmio to/from the CX23418 so boards work in older systems

cx18: Throttle mmio to/from the CX23418 so boards work in older systems.  The
CX23418 couldn't reliably handle mmio at the rate at which the cx18 driver was
attempting to access the chip.  The PCI bridge arrangements and settings on
modern motherboards still allowed the CX23418 to work OK, but it didn't work
well on many older motherboards: mysterious I2C errors, firmware loading errors,
etc.  This patch adds a throttle to *all* mmio access to the CX23418.  It
defaults to a delay of 31 ns, but is adjustable by the mmio_ndelay module parm.
My HVR-1600 and Raptor PAL/SECAM card now function for analog capture on a
motherboard with an Intel 82810E Northbridge and 82801AA Southbridge.

Signed-off-by: Andy Walls <awalls@radix.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 17 insertions, 1 deletions

diff --git a/drivers/media/video/cx18/cx18-driver.c b/drivers/media/video/cx18/cx18-driver.c
index d31e1ec8d14c..202b28190148 100644
--- a/drivers/media/video/cx18/cx18-driver.c
+++ b/drivers/media/video/cx18/cx18-driver.c
@@ -4,6 +4,7 @@
  *  Derived from ivtv-driver.c
  *
  *  Copyright (C) 2007  Hans Verkuil <hverkuil@xs4all.nl>
+ *  Copyright (C) 2008  Andy Walls <awalls@radix.net>
  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
@@ -74,10 +75,14 @@ static int radio[CX18_MAX_CARDS] = { -1, -1, -1, -1, -1, -1, -1, -1,
                                      -1, -1, -1, -1, -1, -1, -1, -1,
                                      -1, -1, -1, -1, -1, -1, -1, -1,
                                      -1, -1, -1, -1, -1, -1, -1, -1 };
-
+static int mmio_ndelay[CX18_MAX_CARDS] = { -1, -1, -1, -1, -1, -1, -1, -1,
+                                           -1, -1, -1, -1, -1, -1, -1, -1,
+                                           -1, -1, -1, -1, -1, -1, -1, -1,
+                                           -1, -1, -1, -1, -1, -1, -1, -1 };
 static unsigned cardtype_c = 1;
 static unsigned tuner_c = 1;
 static unsigned radio_c = 1;
+static int mmio_ndelay_c = 1;
 static char pal[] = "--";
 static char secam[] = "--";
 static char ntsc[] = "-";
@@ -96,6 +101,7 @@ int cx18_debug;
 module_param_array(tuner, int, &tuner_c, 0644);
 module_param_array(radio, bool, &radio_c, 0644);
 module_param_array(cardtype, int, &cardtype_c, 0644);
+module_param_array(mmio_ndelay, int, &mmio_ndelay_c, 0644);
 module_param_string(pal, pal, sizeof(pal), 0644);
 module_param_string(secam, secam, sizeof(secam), 0644);
 module_param_string(ntsc, ntsc, sizeof(ntsc), 0644);
@@ -141,6 +147,11 @@ MODULE_PARM_DESC(debug,
 MODULE_PARM_DESC(cx18_pci_latency,
                  "Change the PCI latency to 64 if lower: 0 = No, 1 = Yes,\n"
                  "\t\t\tDefault: Yes");
+MODULE_PARM_DESC(mmio_ndelay,
+                 "Delay (ns) for each CX23418 memory mapped IO access.\n"
+                 "\t\t\tTry larger values that are close to a multiple of the\n"
+                 "\t\t\tPCI clock period, 30.3 ns, if your card doesn't work.\n"
+                 "\t\t\tDefault: " __stringify(CX18_DEFAULT_MMIO_NDELAY));
 MODULE_PARM_DESC(enc_mpg_buffers,
                  "Encoder MPG Buffers (in MB)\n"
                  "\t\t\tDefault: " __stringify(CX18_DEFAULT_ENC_MPG_BUFFERS));
@@ -357,6 +368,11 @@ static void cx18_process_options(struct cx18 *cx)
         cx->options.tuner = tuner[cx->num];
         cx->options.radio = radio[cx->num];
 
+        if (mmio_ndelay[cx->num] < 0)
+                cx->options.mmio_ndelay = CX18_DEFAULT_MMIO_NDELAY;
+        else
+                cx->options.mmio_ndelay = mmio_ndelay[cx->num];
+
         cx->std = cx18_parse_std(cx);
         if (cx->options.cardtype == -1) {
                 CX18_INFO("Ignore card\n");