From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966643AbdAFP5I (ORCPT ); Fri, 6 Jan 2017 10:57:08 -0500 Received: from mail-yw0-f176.google.com ([209.85.161.176]:35602 "EHLO mail-yw0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754882AbdAFP47 (ORCPT ); Fri, 6 Jan 2017 10:56:59 -0500 MIME-Version: 1.0 In-Reply-To: <20170106143029.11553-4-tomeu.vizoso@collabora.com> References: <20170106143029.11553-1-tomeu.vizoso@collabora.com> <20170106143029.11553-4-tomeu.vizoso@collabora.com> From: Sean Paul Date: Fri, 6 Jan 2017 10:56:31 -0500 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v3 3/5] drm/dp: add helpers for capture of frame CRCs To: Tomeu Vizoso Cc: Linux Kernel Mailing List , =?UTF-8?B?VmlsbGUgU3lyasOkbMOk?= , Thierry Reding , intel-gfx-trybot@lists.freedesktop.org, Emil Velikov , Daniel Vetter , Benjamin Gaignard , Jani Nikula , dri-devel , David Airlie Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jan 6, 2017 at 9:30 AM, Tomeu Vizoso wrote: > Adds helpers for starting and stopping capture of frame CRCs through the > DPCD. When capture is on, a worker waits for vblanks and retrieves the > frame CRC to put it in the queue on the CRTC that is using the > eDP connector, so it's passed to userspace. > > v2: Reuse drm_crtc_wait_one_vblank > Update locking, as drm_crtc_add_crc_entry now takes the lock > > v3: Don't call wake_up_interruptible directly, that's now done in > drm_crtc_add_crc_entry. > > Signed-off-by: Tomeu Vizoso > --- > > drivers/gpu/drm/drm_dp_helper.c | 118 ++++++++++++++++++++++++++++++++++++++++ > include/drm/drm_dp_helper.h | 7 +++ > 2 files changed, 125 insertions(+) > > diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c > index 3e6fe82c6d64..e531f1317268 100644 > --- a/drivers/gpu/drm/drm_dp_helper.c > +++ b/drivers/gpu/drm/drm_dp_helper.c > @@ -981,6 +981,74 @@ static const struct i2c_lock_operations drm_dp_i2c_lock_ops = { > .unlock_bus = unlock_bus, > }; > > +static int drm_dp_aux_get_crc(struct drm_dp_aux *aux, u8 *crc) > +{ > + u8 buf, count; > + int ret; > + > + ret = drm_dp_dpcd_readb(aux, DP_TEST_SINK, &buf); > + if (ret < 0) > + return ret; > + > + WARN_ON(!(buf & DP_TEST_SINK_START)); > + > + ret = drm_dp_dpcd_readb(aux, DP_TEST_SINK_MISC, &buf); > + if (ret < 0) > + return ret; > + > + count = buf & DP_TEST_COUNT_MASK; > + if (count == aux->crc_count) > + return -EAGAIN; /* No CRC yet */ > + > + aux->crc_count = count; > + > + /* At DP_TEST_CRC_R_CR, there's 6 bytes containing CRC data, 2 bytes > + * per component (RGB or CrYCb). nit: doesn't conform to CodingStyle > + */ > + ret = drm_dp_dpcd_read(aux, DP_TEST_CRC_R_CR, crc, 6); > + if (ret < 0) > + return ret; > + > + return 0; > +} > + > +static void drm_dp_aux_crc_work(struct work_struct *work) > +{ > + struct drm_dp_aux *aux = container_of(work, struct drm_dp_aux, > + crc_work); > + struct drm_crtc *crtc; > + u8 crc_bytes[6]; > + uint32_t crcs[3]; > + int ret; > + > + if (WARN_ON(!aux->connector)) > + return; > + > + crtc = aux->connector->state->crtc; > + while (crtc->crc.opened) { > + drm_crtc_wait_one_vblank(crtc); > + if (!crtc->crc.opened) > + break; > + > + ret = drm_dp_aux_get_crc(aux, crc_bytes); > + if (ret == -EAGAIN) { > + usleep_range(1000, 2000); > + ret = drm_dp_aux_get_crc(aux, crc_bytes); > + } > + > + if (ret) { > + DRM_DEBUG_KMS("Failed to get a CRC even after retrying: %d\n", > + ret); > + continue; > + } I think it'd be better to restructure this to only call drm_dp_aux_get_crc in one place (and differentiate between EAGAIN and other failures): bool retry = false; while (...) { ... ret = drm_dp_aux_get_crc(aux, crc_bytes); if (ret == -EAGAIN) { if (retry) DRM_DEBUG_KMS("Get CRC failed after retrying: %d\n", ret); retry = !retry; usleep_range(1000, 2000); continue; } retry = false; if (!ret) { crcs[0] = crc_bytes[0] | crc_bytes[1] << 8; crcs[1] = crc_bytes[2] | crc_bytes[3] << 8; crcs[2] = crc_bytes[4] | crc_bytes[5] << 8; ret = drm_crtc_add_crc_entry(crtc, false, 0, crcs); if (ret) DRM_DEBUG_KMS("Failed to add crc entry %d\n", ret); } else { DRM_DEBUG_KMS("Get CRC failed: %d\n", ret); } } > + > + crcs[0] = crc_bytes[0] | crc_bytes[1] << 8; > + crcs[1] = crc_bytes[2] | crc_bytes[3] << 8; > + crcs[2] = crc_bytes[4] | crc_bytes[5] << 8; > + ret = drm_crtc_add_crc_entry(crtc, false, 0, crcs); > + } > +} > + > /** > * drm_dp_aux_init() - minimally initialise an aux channel > * @aux: DisplayPort AUX channel > @@ -993,6 +1061,7 @@ static const struct i2c_lock_operations drm_dp_i2c_lock_ops = { > void drm_dp_aux_init(struct drm_dp_aux *aux) > { > mutex_init(&aux->hw_mutex); > + INIT_WORK(&aux->crc_work, drm_dp_aux_crc_work); > > aux->ddc.algo = &drm_dp_i2c_algo; > aux->ddc.algo_data = aux; > @@ -1081,3 +1150,52 @@ int drm_dp_psr_setup_time(const u8 psr_cap[EDP_PSR_RECEIVER_CAP_SIZE]) > EXPORT_SYMBOL(drm_dp_psr_setup_time); > > #undef PSR_SETUP_TIME > + > +/** > + * drm_dp_start_crc() - start capture of frame CRCs > + * @aux: DisplayPort AUX channel > + * > + * Returns 0 on success or a negative error code on failure. > + */ > +int drm_dp_start_crc(struct drm_dp_aux *aux) > +{ > + u8 buf; > + int ret; > + > + ret = drm_dp_dpcd_readb(aux, DP_TEST_SINK, &buf); > + if (ret < 0) > + return ret; > + > + ret = drm_dp_dpcd_writeb(aux, DP_TEST_SINK, buf | DP_TEST_SINK_START); > + if (ret < 0) > + return ret; > + > + aux->crc_count = 0; > + schedule_work(&aux->crc_work); > + > + return 0; > +} > +EXPORT_SYMBOL(drm_dp_start_crc); > + > +/** > + * drm_dp_stop_crc() - stop capture of frame CRCs > + * @aux: DisplayPort AUX channel > + * > + * Returns 0 on success or a negative error code on failure. > + */ > +int drm_dp_stop_crc(struct drm_dp_aux *aux) > +{ > + u8 buf; > + int ret; > + > + ret = drm_dp_dpcd_readb(aux, DP_TEST_SINK, &buf); > + if (ret < 0) > + return ret; > + > + ret = drm_dp_dpcd_writeb(aux, DP_TEST_SINK, buf & ~DP_TEST_SINK_START); > + if (ret < 0) > + return ret; > + Can we flush the worker here to head off any races? > + return 0; > +} > +EXPORT_SYMBOL(drm_dp_stop_crc); > diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h > index 4fa77b434594..276e1ecd947b 100644 > --- a/include/drm/drm_dp_helper.h > +++ b/include/drm/drm_dp_helper.h > @@ -723,6 +723,8 @@ struct drm_dp_aux_msg { > * @dev: pointer to struct device that is the parent for this AUX channel > * @connector: backpointer to connector that uses this AUX channel > * @hw_mutex: internal mutex used for locking transfers > + * @crc_work: worker that captures CRCs for each frame > + * @crc_count: counter of captured frame CRCs > * @transfer: transfers a message representing a single AUX transaction > * > * The .dev field should be set to a pointer to the device that implements > @@ -760,6 +762,8 @@ struct drm_dp_aux { > struct device *dev; > struct drm_connector *connector; > struct mutex hw_mutex; > + struct work_struct crc_work; > + u8 crc_count; > ssize_t (*transfer)(struct drm_dp_aux *aux, > struct drm_dp_aux_msg *msg); > /** > @@ -838,4 +842,7 @@ void drm_dp_aux_init(struct drm_dp_aux *aux); > int drm_dp_aux_register(struct drm_dp_aux *aux); > void drm_dp_aux_unregister(struct drm_dp_aux *aux); > > +int drm_dp_start_crc(struct drm_dp_aux *aux); > +int drm_dp_stop_crc(struct drm_dp_aux *aux); > + > #endif /* _DRM_DP_HELPER_H_ */ > -- > 2.9.3 > -- Sean Paul, Software Engineer, Google / Chromium OS