Re: [PATCH] drm/dp: Correctly mask DP_TRAINING_AUX_RD_INTERVAL values for DP 1.4

Benson Leung
2018-03-08T00:36:21Z

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Hey Matt,

Your patch doesn't build. Missing semicolon, dude.

On Wed, Mar 07, 2018 at 04:13:58PM -0800, matthew.s.atwood@intel.com wrote:
> From: Matt Atwood <matthew.s.atwood@intel.com>
>
> DP_TRAINING_AUX_RD_INTERVAL with DP 1.3 spec changed bit scheeme from 8
> bits to 7 in DPCD 0x000e. The 8th bit is used to identify extended
> receiver capabilities. For panels that use this new feature wait interval
> would be increased by 512 ms, when spec is max 16 ms. This behavior is
> described in table 2-158 of DP 1.4 spec address 0000eh.
>
> With the introduction of DP 1.4 spec main link clock recovery was
> standardized to 100 us regardless of TRAINING_AUX_RD_INTERVAL value.
>
> To avoid breaking panels that are not spec compiant we now warn on
> invalid values.
>
> V2: commit title/message, masking all 7 bits, warn on out of spec values.
> V3: commit message, make link train clock recovery follow DP 1.4 spec.
> V4: style changes
>
> Signed-off-by: Matt Atwood <matthew.s.atwood@intel.com>
> ---
> drivers/gpu/drm/drm_dp_helper.c | 18 ++++++++++++++----
> include/drm/drm_dp_helper.h | 6 ++++++
> 2 files changed, 20 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
> index adf79be..6985ff3 100644
> --- a/drivers/gpu/drm/drm_dp_helper.c
> +++ b/drivers/gpu/drm/drm_dp_helper.c
> @@ -119,18 +119,28 @@ u8 drm_dp_get_adjust_request_pre_emphasis(const u8 link_status[DP_LINK_STATUS_SI
> EXPORT_SYMBOL(drm_dp_get_adjust_request_pre_emphasis);
>
> void drm_dp_link_train_clock_recovery_delay(const u8 dpcd[DP_RECEIVER_CAP_SIZE]) {
> - if (dpcd[DP_TRAINING_AUX_RD_INTERVAL] == 0)
> + int rd_interval = dpcd[DP_TRAINING_AUX_RD_INTERVAL] & DP_TRAINING_AUX_RD_MASK;
> +
> + if (rd_interval > 4)
> + DRM_DEBUG_KMS("AUX interval %d, out of range (max 4)", rd_interval);
> +
> + if (rd_interval == 0 || (dpcd[DP_DPCD_REV] >= DP_REV_14))
> udelay(100);
> else
> - mdelay(dpcd[DP_TRAINING_AUX_RD_INTERVAL] * 4);
> + mdelay(rd_interval * 4)

Need a semicolon here.

/mnt/host/source/src/third_party/kernel/v4.14/drivers/gpu/drm/drm_dp_helper.c: In function 'drm_dp_link_train_clock_recovery_delay':
/mnt/host/source/src/third_party/kernel/v4.14/drivers/gpu/drm/drm_dp_helper.c:131:1: error: expected ';' before '}' token
}
^
make[4]: *** [/mnt/host/source/src/third_party/kernel/v4.14/scripts/Makefile.build:320: drivers/gpu/drm/drm_dp_helper.o] Error 1

Thanks,
Benson

--
Benson Leung
Staff Software Engineer
Chrome OS Kernel
Google Inc.
bleung@google.com
Chromium OS Project
bleung@chromium.org

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