From the CI builds, its been observed that during a driver
reload/insert, dp dual mode read function sometimes fails to
read from LSPCON device over i2c-over-aux channel.
This patch:
- adds some delay and few retries, allowing a scope for these
devices to settle down and respond.
- changes one error log's level from ERROR->DEBUG as we want
to call it an error only after all the retries are exhausted.
V2: Addressed review comments from Jani (for loop for retry)
V3: Addressed review comments from Imre (break on partial read too)
V3: Addressed review comments from Ville/Imre (Add the retries
exclusively for LSPCON, not for all dp_dual_mode devices)
V4: Added r-b from Imre, sending it to dri-devel (Jani)
Cc: Ville Syrjala <ville.syrj...@linux.intel.com>
Cc: Imre Deak <imre.d...@intel.com>
Cc: Jani Nikula <jani.nik...@linux.intel.com>
Reviewed-by: Imre Deak <imre.d...@intel.com>
Signed-off-by: Shashank Sharma <shashank.sha...@intel.com>
---
drivers/gpu/drm/drm_dp_dual_mode_helper.c | 16 +++++++++++++---
1 file changed, 13 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 0ef9011..02a5092 100644
--- a/drivers/gpu/drm/drm_dp_dual_mode_helper.c
+++ b/drivers/gpu/drm/drm_dp_dual_mode_helper.c
@@ -410,6 +410,7 @@ int drm_lspcon_get_mode(struct i2c_adapter *adapter,
{
u8 data;
int ret = 0;
+ int retry;
if (!mode) {
DRM_ERROR("NULL input\n");
@@ -417,10 +418,19 @@ 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 = 0; retry < 6; retry++) {
+ if (retry)
+ usleep_range(500, 1000);
+
+ ret = drm_dp_dual_mode_read(adapter,
+ DP_DUAL_MODE_LSPCON_CURRENT_MODE,
+ &data, sizeof(data));
+ if (!ret)
+ break;
+ }
+
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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