V4L/DVB (9110): cx18: Add default behavior of checking and retrying PCI MMIO accesses

cx18: Add default behavior of checking and retrying PCI MMIO accesses.
The concept of checking and retrying PCI MMIO accesses for better reliability
in older motherboards was suggested by Steve Toth <stoth@linuxtv.org>.  This
change implements MMIO retries and the retry_mmio module parameter that is
enabled by default.  Limited experiments have shown this is more reliable than
the mmio_ndelay parameter.  mmio_ndelay has insignificant effect with retries
enabled.

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

1 files changed, 7 insertions, 0 deletions

diff --git a/drivers/media/video/cx18/cx18-driver.c b/drivers/media/video/cx18/cx18-driver.c
index 4de7b501f207..df5531709ae5 100644
--- a/drivers/media/video/cx18/cx18-driver.c
+++ b/drivers/media/video/cx18/cx18-driver.c
@@ -96,6 +96,7 @@ static int enc_pcm_buffers = CX18_DEFAULT_ENC_PCM_BUFFERS;
 
 static int cx18_pci_latency = 1;
 
+int cx18_retry_mmio = 1;
 int cx18_debug;
 
 module_param_array(tuner, int, &tuner_c, 0644);
@@ -106,6 +107,7 @@ module_param_string(pal, pal, sizeof(pal), 0644);
 module_param_string(secam, secam, sizeof(secam), 0644);
 module_param_string(ntsc, ntsc, sizeof(ntsc), 0644);
 module_param_named(debug, cx18_debug, int, 0644);
+module_param_named(retry_mmio, cx18_retry_mmio, int, 0644);
 module_param(cx18_pci_latency, int, 0644);
 module_param(cx18_first_minor, int, 0644);
 
@@ -147,6 +149,9 @@ 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(retry_mmio,
+                 "Check and retry memory mapped IO accesses\n"
+                 "\t\t\tDefault: 1 [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"
@@ -827,6 +832,7 @@ err:
         if (retval == 0)
                 retval = -ENODEV;
         CX18_ERR("Error %d on initialization\n", retval);
+        cx18_log_statistics(cx);
 
         kfree(cx18_cards[cx18_cards_active]);
         cx18_cards[cx18_cards_active] = NULL;
@@ -931,6 +937,7 @@ static void cx18_remove(struct pci_dev *pci_dev)
 
         pci_disable_device(cx->dev);
 
+        cx18_log_statistics(cx);
         CX18_INFO("Removed %s, card #%d\n", cx->card_name, cx->num);
 }