It's an observation during some CI tests that few LSPCON chips
respond slow while system is under load, and need some delay
while reading current mode status using i2c-over-aux channel.
This patch:
- Adds few retries and delays before declaring a read
failure from LSPCON hardware.
- Changes the debug level of the print from ERROR->DEBUG
whereas another patch in I915 will add an ERROR message
from the caller when we have timed out all our limits.
V2: addressed review comments from Imre, and added r-b
- use int instead of u8 for counter
- use for loop instead of do...while();
V3: Rebase
Cc: Ville Syrjala <ville.syrjala@xxxxxxxxxxxxxxx>
Cc: Imre Deak <imre.deak@xxxxxxxxx>
Reviewed-by: Imre Deak <imre.deak@xxxxxxxxx>
Signed-off-by: Shashank Sharma <shashank.sharma@xxxxxxxxx>
Signed-off-by: Mahesh Kumar <mahesh1.kumar@xxxxxxxxx>
---
drivers/gpu/drm/drm_dp_dual_mode_helper.c | 14 +++++++++++---
1 file changed, 11 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/drm_dp_dual_mode_helper.c b/drivers/gpu/drm/drm_dp_dual_mode_helper.c
index 80e62f6..fc8c7ac 100644
--- a/drivers/gpu/drm/drm_dp_dual_mode_helper.c
+++ b/drivers/gpu/drm/drm_dp_dual_mode_helper.c
@@ -409,6 +409,7 @@ int drm_lspcon_get_mode(struct i2c_adapter *adapter,
enum drm_lspcon_mode *mode)
{
u8 data;
+ int retry;
int ret = 0;
if (!mode) {
@@ -417,10 +418,17 @@ int drm_lspcon_get_mode(struct i2c_adapter *adapter,
}
/* Read Status: i2c over aux */
- ret = drm_dp_dual_mode_read(adapter, DP_DUAL_MODE_LSPCON_CURRENT_MODE,
- &data, sizeof(data));
+ for (retry = 5; ; retry--) {
+ ret = drm_dp_dual_mode_read(adapter,
+ DP_DUAL_MODE_LSPCON_CURRENT_MODE,
+ &data, sizeof(data));
+ if (!ret || !retry)
+ break;
+ usleep_range(500, 1000);
+ }
+
if (ret < 0) {
- DRM_ERROR("LSPCON read(0x80, 0x41) failed\n");
+ DRM_DEBUG_KMS("LSPCON read(0x80, 0x41) failed\n");
return -EFAULT;
}
--
2.7.4
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