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[166.177.185.175]) by smtp.gmail.com with ESMTPSA id o25sm23855350qkm.42.2020.08.19.08.29.15 (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Wed, 19 Aug 2020 08:29:15 -0700 (PDT) Date: Wed, 19 Aug 2020 11:29:14 -0400 From: Sean Paul To: Lyude Paul Cc: nouveau@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, Thomas Zimmermann , Juha-Pekka Heikkila , David Airlie , Lucas De Marchi , open list , Gwan-gyeong Mun , Manasi Navare , Uma Shankar , Rodrigo Vivi , =?iso-8859-1?Q?Jos=E9?= Roberto de Souza , Animesh Manna , Wambui Karuga Subject: Re: [RFC 19/20] drm/i915/dp: Extract drm_dp_read_dpcd_caps() Message-ID: <20200819152914.GE46474@art_vandelay> References: <20200811200457.134743-1-lyude@redhat.com> <20200811200457.134743-20-lyude@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200811200457.134743-20-lyude@redhat.com> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 11, 2020 at 04:04:56PM -0400, Lyude Paul wrote: > Since DP 1.3, it's been possible for DP receivers to specify an > additional set of DPCD capabilities, which can take precedence over the > capabilities reported at DP_DPCD_REV. > > Basically any device supporting DP is going to need to read these in an > identical manner, in particular nouveau, so let's go ahead and just move > this code out of i915 into a shared DRM DP helper that we can use in > other drivers. > > Signed-off-by: Lyude Paul > --- > drivers/gpu/drm/drm_dp_helper.c | 76 +++++++++++++++++++++ > drivers/gpu/drm/i915/display/intel_dp.c | 60 +--------------- > drivers/gpu/drm/i915/display/intel_dp.h | 1 - > drivers/gpu/drm/i915/display/intel_lspcon.c | 2 +- > include/drm/drm_dp_helper.h | 3 + > 5 files changed, 82 insertions(+), 60 deletions(-) > > diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c > index 0ff2959c8f8e8..f9445915c6c26 100644 > --- a/drivers/gpu/drm/drm_dp_helper.c > +++ b/drivers/gpu/drm/drm_dp_helper.c > @@ -423,6 +423,82 @@ bool drm_dp_send_real_edid_checksum(struct drm_dp_aux *aux, > } > EXPORT_SYMBOL(drm_dp_send_real_edid_checksum); > > +static int drm_dp_read_extended_dpcd_caps(struct drm_dp_aux *aux, > + u8 dpcd[DP_RECEIVER_CAP_SIZE]) > +{ > + u8 dpcd_ext[6]; > + int ret; > + > + /* > + * Prior to DP1.3 the bit represented by > + * DP_EXTENDED_RECEIVER_CAP_FIELD_PRESENT was reserved. > + * If it is set DP_DPCD_REV at 0000h could be at a value less than > + * the true capability of the panel. The only way to check is to > + * then compare 0000h and 2200h. > + */ > + if (!(dpcd[DP_TRAINING_AUX_RD_INTERVAL] & > + DP_EXTENDED_RECEIVER_CAP_FIELD_PRESENT)) > + return 0; > + > + ret = drm_dp_dpcd_read(aux, DP_DP13_DPCD_REV, &dpcd_ext, > + sizeof(dpcd_ext)); > + if (ret != sizeof(dpcd_ext)) > + return -EIO; > + > + if (dpcd[DP_DPCD_REV] > dpcd_ext[DP_DPCD_REV]) { > + DRM_DEBUG_KMS("%s: Extended DPCD rev less than base DPCD rev (%d > %d)\n", > + aux->name, dpcd[DP_DPCD_REV], > + dpcd_ext[DP_DPCD_REV]); Might be a good opportunity to convert all of these to drm_dbg_dp()? > + return 0; > + } > + > + if (!memcmp(dpcd, dpcd_ext, sizeof(dpcd_ext))) > + return 0; > + > + DRM_DEBUG_KMS("%s: Base DPCD: %*ph\n", > + aux->name, DP_RECEIVER_CAP_SIZE, dpcd); > + > + memcpy(dpcd, dpcd_ext, sizeof(dpcd_ext)); > + > + return 0; > +} > + > +/** > + * drm_dp_read_dpcd_caps() - read DPCD caps and extended DPCD caps if > + * available > + * @aux: DisplayPort AUX channel > + * @dpcd: Buffer to store the resulting DPCD in > + * > + * Attempts to read the base DPCD caps for @aux. Additionally, this function > + * checks for and reads the extended DPRX caps (%DP_DP13_DPCD_REV) if > + * present. > + * > + * Returns: %0 if the DPCD was read successfully, negative error code > + * otherwise. > + */ > +int drm_dp_read_dpcd_caps(struct drm_dp_aux *aux, > + u8 dpcd[DP_RECEIVER_CAP_SIZE]) > +{ > + int ret; > + > + ret = drm_dp_dpcd_read(aux, DP_DPCD_REV, dpcd, DP_RECEIVER_CAP_SIZE); > + if (ret != DP_RECEIVER_CAP_SIZE || dpcd[DP_DPCD_REV] == 0) > + return -EIO; > + > + ret = drm_dp_read_extended_dpcd_caps(aux, dpcd); > + if (ret < 0) > + return ret; I wonder if we should just go with the "regular" dpcd caps we just read in this case? Regardless of my nits, Reviewed-by: Sean Paul > + > + DRM_DEBUG_KMS("%s: DPCD: %*ph\n", > + aux->name, DP_RECEIVER_CAP_SIZE, dpcd); > + > + if (dpcd[DP_DPCD_REV] == 0) > + ret = -EIO; > + > + return ret; > +} > +EXPORT_SYMBOL(drm_dp_read_dpcd_caps); > + > /** > * drm_dp_downstream_read_info() - read DPCD downstream port info if available > * @aux: DisplayPort AUX channel > diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c > index e343965a483df..230aa0360dc61 100644 > --- a/drivers/gpu/drm/i915/display/intel_dp.c > +++ b/drivers/gpu/drm/i915/display/intel_dp.c > @@ -4449,62 +4449,6 @@ intel_dp_link_down(struct intel_encoder *encoder, > } > } > > -static void > -intel_dp_extended_receiver_capabilities(struct intel_dp *intel_dp) > -{ > - struct drm_i915_private *i915 = dp_to_i915(intel_dp); > - u8 dpcd_ext[6]; > - > - /* > - * Prior to DP1.3 the bit represented by > - * DP_EXTENDED_RECEIVER_CAP_FIELD_PRESENT was reserved. > - * if it is set DP_DPCD_REV at 0000h could be at a value less than > - * the true capability of the panel. The only way to check is to > - * then compare 0000h and 2200h. > - */ > - if (!(intel_dp->dpcd[DP_TRAINING_AUX_RD_INTERVAL] & > - DP_EXTENDED_RECEIVER_CAP_FIELD_PRESENT)) > - return; > - > - if (drm_dp_dpcd_read(&intel_dp->aux, DP_DP13_DPCD_REV, > - &dpcd_ext, sizeof(dpcd_ext)) != sizeof(dpcd_ext)) { > - drm_err(&i915->drm, > - "DPCD failed read at extended capabilities\n"); > - return; > - } > - > - if (intel_dp->dpcd[DP_DPCD_REV] > dpcd_ext[DP_DPCD_REV]) { > - drm_dbg_kms(&i915->drm, > - "DPCD extended DPCD rev less than base DPCD rev\n"); > - return; > - } > - > - if (!memcmp(intel_dp->dpcd, dpcd_ext, sizeof(dpcd_ext))) > - return; > - > - drm_dbg_kms(&i915->drm, "Base DPCD: %*ph\n", > - (int)sizeof(intel_dp->dpcd), intel_dp->dpcd); > - > - memcpy(intel_dp->dpcd, dpcd_ext, sizeof(dpcd_ext)); > -} > - > -bool > -intel_dp_read_dpcd(struct intel_dp *intel_dp) > -{ > - struct drm_i915_private *i915 = dp_to_i915(intel_dp); > - > - if (drm_dp_dpcd_read(&intel_dp->aux, 0x000, intel_dp->dpcd, > - sizeof(intel_dp->dpcd)) < 0) > - return false; /* aux transfer failed */ > - > - intel_dp_extended_receiver_capabilities(intel_dp); > - > - drm_dbg_kms(&i915->drm, "DPCD: %*ph\n", (int)sizeof(intel_dp->dpcd), > - intel_dp->dpcd); > - > - return intel_dp->dpcd[DP_DPCD_REV] != 0; > -} > - > bool intel_dp_get_colorimetry_status(struct intel_dp *intel_dp) > { > u8 dprx = 0; > @@ -4563,7 +4507,7 @@ intel_edp_init_dpcd(struct intel_dp *intel_dp) > /* this function is meant to be called only once */ > drm_WARN_ON(&dev_priv->drm, intel_dp->dpcd[DP_DPCD_REV] != 0); > > - if (!intel_dp_read_dpcd(intel_dp)) > + if (drm_dp_read_dpcd_caps(&intel_dp->aux, intel_dp->dpcd) != 0) > return false; > > drm_dp_read_desc(&intel_dp->aux, &intel_dp->desc, > @@ -4650,7 +4594,7 @@ intel_dp_get_dpcd(struct intel_dp *intel_dp) > { > int ret; > > - if (!intel_dp_read_dpcd(intel_dp)) > + if (drm_dp_read_dpcd_caps(&intel_dp->aux, intel_dp->dpcd)) > return false; > > /* > diff --git a/drivers/gpu/drm/i915/display/intel_dp.h b/drivers/gpu/drm/i915/display/intel_dp.h > index b901ab850cbd9..0a3af3410d52e 100644 > --- a/drivers/gpu/drm/i915/display/intel_dp.h > +++ b/drivers/gpu/drm/i915/display/intel_dp.h > @@ -99,7 +99,6 @@ bool intel_dp_source_supports_hbr3(struct intel_dp *intel_dp); > bool > intel_dp_get_link_status(struct intel_dp *intel_dp, u8 *link_status); > > -bool intel_dp_read_dpcd(struct intel_dp *intel_dp); > bool intel_dp_get_colorimetry_status(struct intel_dp *intel_dp); > int intel_dp_link_required(int pixel_clock, int bpp); > int intel_dp_max_data_rate(int max_link_clock, int max_lanes); > diff --git a/drivers/gpu/drm/i915/display/intel_lspcon.c b/drivers/gpu/drm/i915/display/intel_lspcon.c > index b781bf4696443..dc1b35559afdf 100644 > --- a/drivers/gpu/drm/i915/display/intel_lspcon.c > +++ b/drivers/gpu/drm/i915/display/intel_lspcon.c > @@ -571,7 +571,7 @@ bool lspcon_init(struct intel_digital_port *dig_port) > return false; > } > > - if (!intel_dp_read_dpcd(dp)) { > + if (drm_dp_read_dpcd_caps(&dp->aux, dp->dpcd) != 0) { > DRM_ERROR("LSPCON DPCD read failed\n"); > return false; > } > diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h > index 0c141fc81aaa8..11649e93e5bb6 100644 > --- a/include/drm/drm_dp_helper.h > +++ b/include/drm/drm_dp_helper.h > @@ -1607,6 +1607,9 @@ static inline ssize_t drm_dp_dpcd_writeb(struct drm_dp_aux *aux, > return drm_dp_dpcd_write(aux, offset, &value, 1); > } > > +int drm_dp_read_dpcd_caps(struct drm_dp_aux *aux, > + u8 dpcd[DP_RECEIVER_CAP_SIZE]); > + > int drm_dp_dpcd_read_link_status(struct drm_dp_aux *aux, > u8 status[DP_LINK_STATUS_SIZE]); > > -- > 2.26.2 > > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/dri-devel -- Sean Paul, Software Engineer, Google / Chromium OS