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, 11 insertions, 0 deletions

diff --git a/drivers/media/video/cx18/cx18-av-core.c b/drivers/media/video/cx18/cx18-av-core.c
index d8626e35465..73f5141a42d 100644
--- a/drivers/media/video/cx18/cx18-av-core.c
+++ b/drivers/media/video/cx18/cx18-av-core.c
@@ -42,6 +42,12 @@ int cx18_av_write4(struct cx18 *cx, u16 addr, u32 value)
         return 0;
 }
 
+int cx18_av_write4_noretry(struct cx18 *cx, u16 addr, u32 value)
+{
+        cx18_write_reg_noretry(cx, value, 0xc40000 + addr);
+        return 0;
+}
+
 u8 cx18_av_read(struct cx18 *cx, u16 addr)
 {
         u32 x = cx18_read_reg(cx, 0xc40000 + (addr & ~3));
@@ -55,6 +61,11 @@ u32 cx18_av_read4(struct cx18 *cx, u16 addr)
         return cx18_read_reg(cx, 0xc40000 + addr);
 }
 
+u32 cx18_av_read4_noretry(struct cx18 *cx, u16 addr)
+{
+        return cx18_read_reg_noretry(cx, 0xc40000 + addr);
+}
+
 int cx18_av_and_or(struct cx18 *cx, u16 addr, unsigned and_mask,
                    u8 or_value)
 {