On Tue, Oct 03, 2017 at 06:51:04PM +0530, Shashank Sharma wrote: > 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 <[email protected]> > Cc: Imre Deak <[email protected]> > Cc: Jani Nikula <[email protected]> > Signed-off-by: Shashank Sharma <[email protected]> > --- > 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 0ef9011..725b298 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; > }
Ville's comment about the penalty for well working adapters still holds. Also I don't think we should care about possibly faulty external adapters until we see one. So this probably means moving the retry to drm_lspcon_get_mode() and lspcon_probe(). --Imre > > -- > 2.7.4 > _______________________________________________ Intel-gfx mailing list [email protected] https://lists.freedesktop.org/mailman/listinfo/intel-gfx
