On Wed, 2018-04-18 at 15:43 -0700, José Roberto de Souza wrote:
> - Doing earlier return when not busy
> - using u32 instead of uint32_t
> - counting from 3 to 0 as it is is the most common in the driver
Hmm. I see more instances that increment the loop variable than the
opposite.
> - using DRM_WARN() instead of WARN()
Why? WARN and WARN_ON's are common afaict
> - adding aux port name to the debug message
Sounds like a good idea.
> - nuking last_status, it is one static variable to all DP ports
> also 2 different aux transactions with the same message size would
> have the same ch_ctl value, if really desired to reduce the number
> of debug messages it should be implemented a per aux ch last_status
Makes sense to do this.
> - no need to sleep in the last try
> - sleeping for 1 aux ch transaction time
Was this determined based on the clock speed or is it in the spec? I
see numbers for timeout, nothing for the transaction itself.
This patch mixes up functional changes with non-functional ones. I'd
prefer you split these changes.
>
> Signed-off-by: José Roberto de Souza <jose.so...@intel.com>
> Cc: Dhinakaran Pandiyan <dhinakaran.pandi...@intel.com>
> ---
>
> New patch in this series.
>
> drivers/gpu/drm/i915/intel_dp.c | 23 ++++++++---------------
> 1 file changed, 8 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_dp.c
> b/drivers/gpu/drm/i915/intel_dp.c
> index a11465c62950..258e23961456 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -1068,28 +1068,21 @@ static bool intel_dp_aux_is_busy(struct
> intel_dp *intel_dp)
> struct drm_i915_private *dev_priv =
> to_i915(intel_dig_port->base.base.dev);
> i915_reg_t ch_ctl;
> - uint32_t status;
> - int try;
> + u32 status;
> + unsigned int try;
>
> ch_ctl = intel_dp->aux_ch_ctl_reg(intel_dp);
>
> - for (try = 0; try < 3; try++) {
> + for (try = 3; try; try--) {
> status = I915_READ_NOTRACE(ch_ctl);
> if ((status & DP_AUX_CH_CTL_SEND_BUSY) == 0)
> - break;
> - msleep(1);
> + return false;
> + if (try > 1)
> + usleep_range(400, 500);
> }
>
> - if (try == 3) {
> - static u32 last_status = -1;
> - const u32 status = I915_READ(ch_ctl);
> -
> - if (status != last_status) {
> - WARN(1, "dp_aux_ch not started status
> 0x%08x\n",
> - status);
> - last_status = status;
> - }
> - }
> + DRM_WARN("DP aux %c is busy 0x%08x\n",
> + aux_ch_name(intel_dp->aux_ch), status);
>
> return true;
> }
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