>From the CI builds, its been observed that during a driver
reload/insert, dp dual mode read function sometimes fails to
read from dual mode devices (like LSPCON) 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)
Cc: Ville Syrjala <ville.syrjala@xxxxxxxxxxxxxxx>
Cc: Imre Deak <imre.deak@xxxxxxxxx>
Cc: Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx>
Signed-off-by: Shashank Sharma <shashank.sharma@xxxxxxxxx>
---
drivers/gpu/drm/drm_dp_dual_mode_helper.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 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..8263660 100644
--- a/drivers/gpu/drm/drm_dp_dual_mode_helper.c
+++ b/drivers/gpu/drm/drm_dp_dual_mode_helper.c
@@ -75,8 +75,16 @@ ssize_t drm_dp_dual_mode_read(struct i2c_adapter *adapter,
},
};
int ret;
+ int retry;
+
+ for (retry = 0; retry < 6; retry++) {
+ if (retry)
+ usleep_range(500, 1000);
+ ret = i2c_transfer(adapter, msgs, ARRAY_SIZE(msgs));
+ if (ret >= 0)
+ break;
+ }
- ret = i2c_transfer(adapter, msgs, ARRAY_SIZE(msgs));
if (ret < 0)
return ret;
if (ret != ARRAY_SIZE(msgs))
@@ -420,7 +428,7 @@ int drm_lspcon_get_mode(struct i2c_adapter *adapter,
ret = drm_dp_dual_mode_read(adapter, DP_DUAL_MODE_LSPCON_CURRENT_MODE,
&data, sizeof(data));
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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