Re: [PATCH 2/2] drm/i915: Get rid of intel_dp_dpcd_read_wake()

From: Jani Nikula
Date: Thu Mar 17 2016 - 13:57:04 EST

On Thu, 17 Mar 2016, Lyude <cpaul@xxxxxxxxxx> wrote:
> Since we've fixed up drm_dp_dpcd_read() to allow for retries when things
> timeout, there's no use for having this function anymore. Good riddens.
>
> Signed-off-by: Lyude <cpaul@xxxxxxxxxx>
> ---
> drivers/gpu/drm/i915/intel_dp.c | 79 ++++++++++++-----------------------------
> 1 file changed, 22 insertions(+), 57 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index cdc2c15..fb4cbbe5 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -3190,47 +3190,14 @@ static void chv_dp_post_pll_disable(struct intel_encoder *encoder)
> }
>
> /*
> - * Native read with retry for link status and receiver capability reads for
> - * cases where the sink may still be asleep.
> - *
> - * Sinks are *supposed* to come up within 1ms from an off state, but we're also
> - * supposed to retry 3 times per the spec.
> - */
> -static ssize_t
> -intel_dp_dpcd_read_wake(struct drm_dp_aux *aux, unsigned int offset,
> - void *buffer, size_t size)
> -{
> - ssize_t ret;
> - int i;
> -
> - /*
> - * Sometime we just get the same incorrect byte repeated
> - * over the entire buffer. Doing just one throw away read
> - * initially seems to "solve" it.
> - */
> - drm_dp_dpcd_read(aux, DP_DPCD_REV, buffer, 1);

Last time around I dug out the commit adding the line above, which fixed
a bug, and said it should be accounted for somehow. But I've had a
change of heart. I want this function gone already. We've improved the
dp helpers considerably, and if this regresses, we need to look at
fixing this either at the drm level or in our ->transfer hook.

Acked-by: Jani Nikula <jani.nikula@xxxxxxxxx>


> -
> - for (i = 0; i < 3; i++) {
> - ret = drm_dp_dpcd_read(aux, offset, buffer, size);
> - if (ret == size)
> - return ret;
> - msleep(1);
> - }
> -
> - return ret;
> -}
> -
> -/*
> * Fetch AUX CH registers 0x202 - 0x207 which contain
> * link status information
> */
> bool
> intel_dp_get_link_status(struct intel_dp *intel_dp, uint8_t link_status[DP_LINK_STATUS_SIZE])
> {
> - return intel_dp_dpcd_read_wake(&intel_dp->aux,
> - DP_LANE0_1_STATUS,
> - link_status,
> - DP_LINK_STATUS_SIZE) == DP_LINK_STATUS_SIZE;
> + return drm_dp_dpcd_read(&intel_dp->aux, DP_LANE0_1_STATUS, link_status,
> + DP_LINK_STATUS_SIZE) == DP_LINK_STATUS_SIZE;
> }
>
> /* These are source-specific values. */
> @@ -3865,8 +3832,8 @@ intel_dp_get_dpcd(struct intel_dp *intel_dp)
> struct drm_i915_private *dev_priv = dev->dev_private;
> uint8_t rev;
>
> - if (intel_dp_dpcd_read_wake(&intel_dp->aux, 0x000, intel_dp->dpcd,
> - sizeof(intel_dp->dpcd)) < 0)
> + if (drm_dp_dpcd_read(&intel_dp->aux, 0x000, intel_dp->dpcd,
> + sizeof(intel_dp->dpcd)) < 0)
> return false; /* aux transfer failed */
>
> DRM_DEBUG_KMS("DPCD: %*ph\n", (int) sizeof(intel_dp->dpcd), intel_dp->dpcd);
> @@ -3877,9 +3844,9 @@ intel_dp_get_dpcd(struct intel_dp *intel_dp)
> /* Check if the panel supports PSR */
> memset(intel_dp->psr_dpcd, 0, sizeof(intel_dp->psr_dpcd));
> if (is_edp(intel_dp)) {
> - intel_dp_dpcd_read_wake(&intel_dp->aux, DP_PSR_SUPPORT,
> - intel_dp->psr_dpcd,
> - sizeof(intel_dp->psr_dpcd));
> + drm_dp_dpcd_read(&intel_dp->aux, DP_PSR_SUPPORT,
> + intel_dp->psr_dpcd,
> + sizeof(intel_dp->psr_dpcd));
> if (intel_dp->psr_dpcd[0] & DP_PSR_IS_SUPPORTED) {
> dev_priv->psr.sink_support = true;
> DRM_DEBUG_KMS("Detected EDP PSR Panel.\n");
> @@ -3890,9 +3857,9 @@ intel_dp_get_dpcd(struct intel_dp *intel_dp)
> uint8_t frame_sync_cap;
>
> dev_priv->psr.sink_support = true;
> - intel_dp_dpcd_read_wake(&intel_dp->aux,
> - DP_SINK_DEVICE_AUX_FRAME_SYNC_CAP,
> - &frame_sync_cap, 1);
> + drm_dp_dpcd_read(&intel_dp->aux,
> + DP_SINK_DEVICE_AUX_FRAME_SYNC_CAP,
> + &frame_sync_cap, 1);
> dev_priv->psr.aux_frame_sync = frame_sync_cap ? true : false;
> /* PSR2 needs frame sync as well */
> dev_priv->psr.psr2_support = dev_priv->psr.aux_frame_sync;
> @@ -3908,15 +3875,13 @@ intel_dp_get_dpcd(struct intel_dp *intel_dp)
> /* Intermediate frequency support */
> if (is_edp(intel_dp) &&
> (intel_dp->dpcd[DP_EDP_CONFIGURATION_CAP] & DP_DPCD_DISPLAY_CONTROL_CAPABLE) &&
> - (intel_dp_dpcd_read_wake(&intel_dp->aux, DP_EDP_DPCD_REV, &rev, 1) == 1) &&
> + (drm_dp_dpcd_read(&intel_dp->aux, DP_EDP_DPCD_REV, &rev, 1) == 1) &&
> (rev >= 0x03)) { /* eDp v1.4 or higher */
> __le16 sink_rates[DP_MAX_SUPPORTED_RATES];
> int i;
>
> - intel_dp_dpcd_read_wake(&intel_dp->aux,
> - DP_SUPPORTED_LINK_RATES,
> - sink_rates,
> - sizeof(sink_rates));
> + drm_dp_dpcd_read(&intel_dp->aux, DP_SUPPORTED_LINK_RATES,
> + sink_rates, sizeof(sink_rates));
>
> for (i = 0; i < ARRAY_SIZE(sink_rates); i++) {
> int val = le16_to_cpu(sink_rates[i]);
> @@ -3939,9 +3904,9 @@ intel_dp_get_dpcd(struct intel_dp *intel_dp)
> if (intel_dp->dpcd[DP_DPCD_REV] == 0x10)
> return true; /* no per-port downstream info */
>
> - if (intel_dp_dpcd_read_wake(&intel_dp->aux, DP_DOWNSTREAM_PORT_0,
> - intel_dp->downstream_ports,
> - DP_MAX_DOWNSTREAM_PORTS) < 0)
> + if (drm_dp_dpcd_read(&intel_dp->aux, DP_DOWNSTREAM_PORT_0,
> + intel_dp->downstream_ports,
> + DP_MAX_DOWNSTREAM_PORTS) < 0)
> return false; /* downstream port status fetch failed */
>
> return true;
> @@ -3955,11 +3920,11 @@ intel_dp_probe_oui(struct intel_dp *intel_dp)
> if (!(intel_dp->dpcd[DP_DOWN_STREAM_PORT_COUNT] & DP_OUI_SUPPORT))
> return;
>
> - if (intel_dp_dpcd_read_wake(&intel_dp->aux, DP_SINK_OUI, buf, 3) == 3)
> + if (drm_dp_dpcd_read(&intel_dp->aux, DP_SINK_OUI, buf, 3) == 3)
> DRM_DEBUG_KMS("Sink OUI: %02hx%02hx%02hx\n",
> buf[0], buf[1], buf[2]);
>
> - if (intel_dp_dpcd_read_wake(&intel_dp->aux, DP_BRANCH_OUI, buf, 3) == 3)
> + if (drm_dp_dpcd_read(&intel_dp->aux, DP_BRANCH_OUI, buf, 3) == 3)
> DRM_DEBUG_KMS("Branch OUI: %02hx%02hx%02hx\n",
> buf[0], buf[1], buf[2]);
> }
> @@ -3975,7 +3940,7 @@ intel_dp_probe_mst(struct intel_dp *intel_dp)
> if (intel_dp->dpcd[DP_DPCD_REV] < 0x12)
> return false;
>
> - if (intel_dp_dpcd_read_wake(&intel_dp->aux, DP_MSTM_CAP, buf, 1)) {
> + if (drm_dp_dpcd_read(&intel_dp->aux, DP_MSTM_CAP, buf, 1)) {
> if (buf[0] & DP_MST_CAP) {
> DRM_DEBUG_KMS("Sink is MST capable\n");
> intel_dp->is_mst = true;
> @@ -4112,7 +4077,7 @@ stop:
> static bool
> intel_dp_get_sink_irq(struct intel_dp *intel_dp, u8 *sink_irq_vector)
> {
> - return intel_dp_dpcd_read_wake(&intel_dp->aux,
> + return drm_dp_dpcd_read(&intel_dp->aux,
> DP_DEVICE_SERVICE_IRQ_VECTOR,
> sink_irq_vector, 1) == 1;
> }
> @@ -4122,7 +4087,7 @@ intel_dp_get_sink_irq_esi(struct intel_dp *intel_dp, u8 *sink_irq_vector)
> {
> int ret;
>
> - ret = intel_dp_dpcd_read_wake(&intel_dp->aux,
> + ret = drm_dp_dpcd_read(&intel_dp->aux,
> DP_SINK_COUNT_ESI,
> sink_irq_vector, 14);
> if (ret != 14)
> @@ -4383,7 +4348,7 @@ intel_dp_detect_dpcd(struct intel_dp *intel_dp)
> intel_dp->downstream_ports[0] & DP_DS_PORT_HPD) {
> uint8_t reg;
>
> - if (intel_dp_dpcd_read_wake(&intel_dp->aux, DP_SINK_COUNT,
> + if (drm_dp_dpcd_read(&intel_dp->aux, DP_SINK_COUNT,
> &reg, 1) < 0)
> return connector_status_unknown;

--
Jani Nikula, Intel Open Source Technology Center