On Tue, Mar 15, 2011 at 7:04 AM, Chris Wilson chris@chris-wilson.co.uk wrote:
Usually EDID retrieval is fine. However, sometimes, especially when the machine is loaded, it fails, but succeeds after a few retries.
Based on a patch by Michael Buesch.
Reported-by: Michael Buesch mb@bu3sch.de Signed-off-by: Chris Wilson chris@chris-wilson.co.uk
Looks good.
Reviewed-by: Alex Deucher alexdeucher@gmail.com
I was going to suggest tuning the i2c_adapter.retries of the affected components, but that only covers EGAIN and not EREMOTEIO/ETIMEDOUT that afflicts us. With the alteration to only retry the transfer of the affected block, this looks to be a reasonable idea and complements the logic to retry corrupted transfers. -Chris
drivers/gpu/drm/drm_edid.c | 44 ++++++++++++++++++++++++++------------------ 1 files changed, 26 insertions(+), 18 deletions(-)
diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c index a245d17..ddc3da9 100644 --- a/drivers/gpu/drm/drm_edid.c +++ b/drivers/gpu/drm/drm_edid.c @@ -230,24 +230,32 @@ drm_do_probe_ddc_edid(struct i2c_adapter *adapter, unsigned char *buf, int block, int len) { unsigned char start = block * EDID_LENGTH;
- struct i2c_msg msgs[] = {
- {
- .addr = DDC_ADDR,
- .flags = 0,
- .len = 1,
- .buf = &start,
- }, {
- .addr = DDC_ADDR,
- .flags = I2C_M_RD,
- .len = len,
- .buf = buf,
- }
- };
- int ret, retries = 5;
- if (i2c_transfer(adapter, msgs, 2) == 2)
- return 0;
- /* The core i2c driver will automatically retry the transfer if the
- * adapter reports EAGAIN. However, we find that bit-banging transfers
- * are susceptible to errors under a heavily loaded machine and
- * generate spurious NAKs and timeouts. Retrying the transfer
- * of the individual block a few times seems to overcome this.
- */
- do {
- struct i2c_msg msgs[] = {
- {
- .addr = DDC_ADDR,
- .flags = 0,
- .len = 1,
- .buf = &start,
- }, {
- .addr = DDC_ADDR,
- .flags = I2C_M_RD,
- .len = len,
- .buf = buf,
- }
- };
- ret = i2c_transfer(adapter, msgs, 2);
- } while (ret != 2 && --retries);
- return -1;
- return ret == 2 ? 0 : -1;
}
static u8 *
1.7.2.3
dri-devel mailing list dri-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/dri-devel