Hi Am 10.02.21 um 09:33 schrieb Khaled Almahallawy:
The number of AUX retries specified in the DP specs is 7. Currently, to make Dell 4k monitors happier, the number of retries are 32. i915 also retries 5 times (intel_dp_aux_xfer) which means in the case of AUX timeout we actually retries 32 * 5 = 160 times.So making the number of aux retires a variable to allow for fine tuning and optimization of aux timing. Signed-off-by: Khaled Almahallawy <khaled.almahall...@intel.com> --- drivers/gpu/drm/drm_dp_helper.c | 10 +++------- include/drm/drm_dp_helper.h | 1 + 2 files changed, 4 insertions(+), 7 deletions(-) diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c index eedbb48815b7..8fdf57b4a06c 100644 --- a/drivers/gpu/drm/drm_dp_helper.c +++ b/drivers/gpu/drm/drm_dp_helper.c @@ -249,13 +249,7 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,mutex_lock(&aux->hw_mutex); - /*- * The specification doesn't give any recommendation on how often to - * retry native transactions. We used to retry 7 times like for - * aux i2c transactions but real world devices this wasn't - * sufficient, bump to 32 which makes Dell 4k monitors happier. - */ - for (retry = 0; retry < 32; retry++) { + for (retry = 0; retry < aux->num_retries; retry++) { if (ret != 0 && ret != -ETIMEDOUT) { usleep_range(AUX_RETRY_INTERVAL, AUX_RETRY_INTERVAL + 100); @@ -1744,6 +1738,8 @@ void drm_dp_aux_init(struct drm_dp_aux *aux) aux->ddc.retries = 3;aux->ddc.lock_ops = &drm_dp_i2c_lock_ops;+ /*Still making the Dell 4k monitors happier*/
The original comment was helpful; this one isn't.Besides that, what problem does this patchset address? Too much probing? If I connect a Dell monitor to an Intel card, how often does it have to probe?
Best regards Thomas
+ aux->num_retries = 32; } EXPORT_SYMBOL(drm_dp_aux_init);diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.hindex edffd1dcca3e..16cbfc8f5e66 100644 --- a/include/drm/drm_dp_helper.h +++ b/include/drm/drm_dp_helper.h @@ -1876,6 +1876,7 @@ struct drm_dp_aux { struct mutex hw_mutex; struct work_struct crc_work; u8 crc_count; + int num_retries; ssize_t (*transfer)(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg); /**
-- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 Nürnberg, Germany (HRB 36809, AG Nürnberg) Geschäftsführer: Felix Imendörffer
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