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| author | Ville Syrjälä <ville.syrjala@linux.intel.com> | 2015-08-26 22:55:07 +0300 |
|---|---|---|
| committer | Jani Nikula <jani.nikula@intel.com> | 2015-09-02 16:13:43 +0300 |
| commit | f36203be608a38a5b5523a7aa52cc72f757b9679 (patch) | |
| tree | a0cc8fdf761f93bcdb61d15ae4d2928457019510 /drivers/gpu/drm/drm_dp_helper.c | |
| parent | 4efa83c8c786ab7ec7982e3dd348cb7e7ecbeb04 (diff) | |
| download | linux-f36203be608a38a5b5523a7aa52cc72f757b9679.tar.xz | |
drm/dp: Add dp_aux_i2c_speed_khz module param to set the assume i2c bus speed
To help with debugging i2c-over-aux issues, add a module parameter than
can be used to tweak the assumed i2c bus speed, and thus the maximum
number of retries we will do for each aux message.
Cc: Simon Farnsworth <simon.farnsworth@onelan.com>
Cc: moosotc@gmail.com
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Simon Farnsworth <simon.farnsworth@onelan.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Diffstat (limited to 'drivers/gpu/drm/drm_dp_helper.c')
| -rw-r--r-- | drivers/gpu/drm/drm_dp_helper.c | 13 |
1 files changed, 10 insertions, 3 deletions
diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c index 214a4c649d56..291734e87fca 100644 --- a/drivers/gpu/drm/drm_dp_helper.c +++ b/drivers/gpu/drm/drm_dp_helper.c @@ -500,6 +500,15 @@ static int drm_dp_i2c_retry_count(const struct drm_dp_aux_msg *msg, } /* + * FIXME currently assumes 10 kHz as some real world devices seem + * to require it. We should query/set the speed via DPCD if supported. + */ +static int dp_aux_i2c_speed_khz __read_mostly = 10; +module_param_unsafe(dp_aux_i2c_speed_khz, int, 0644); +MODULE_PARM_DESC(dp_aux_i2c_speed_khz, + "Assumed speed of the i2c bus in kHz, (1-400, default 10)"); + +/* * Transfer a single I2C-over-AUX message and handle various error conditions, * retrying the transaction as appropriate. It is assumed that the * aux->transfer function does not modify anything in the msg other than the @@ -517,10 +526,8 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg) * before giving up the AUX transaction. * * We also try to account for the i2c bus speed. - * FIXME currently assumes 10 kHz as some real world devices seem - * to require it. We should query/set the speed via DPCD if supported. */ - int max_retries = max(7, drm_dp_i2c_retry_count(msg, 10)); + int max_retries = max(7, drm_dp_i2c_retry_count(msg, dp_aux_i2c_speed_khz)); for (retry = 0, defer_i2c = 0; retry < (max_retries + defer_i2c); retry++) { mutex_lock(&aux->hw_mutex); |