From mboxrd@z Thu Jan 1 00:00:00 1970 From: Heiko Stuebner Subject: Re: [PATCH v5 2/5] drm/dp: fix link probing for devices supporting DP 1.4+ Date: Tue, 25 Sep 2018 13:18:42 +0200 Message-ID: <18095829.BFmvNaydv0@phil> References: <1537866837-4408-1-git-send-email-dkos@cadence.com> <1537866837-4408-3-git-send-email-dkos@cadence.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Return-path: In-Reply-To: <1537866837-4408-3-git-send-email-dkos@cadence.com> Sender: linux-kernel-owner@vger.kernel.org To: Damian Kos Cc: David Airlie , Rob Herring , Mark Rutland , Archit Taneja , Andrzej Hajda , Laurent Pinchart , Gustavo Padovan , Maarten Lankhorst , Sean Paul , Sandy Huang , Quentin Schulz , dri-devel@lists.freedesktop.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-rockchip@lists.infradead.org, pgaj@cadence.com, ltyrala@cadence.com, rafalc@cadence.com, jartur@cadence.com, piotrs@cadence.com, quentin.schulz@bootlin.com, jbergsagel@ti.com List-Id: devicetree@vger.kernel.org Hi Damian, Am Dienstag, 25. September 2018, 11:13:32 CEST schrieb Damian Kos: > From: Quentin Schulz > > DP 1.4 introduced a DP_EXTENDED_RECEIVER_CAP_FIELD_PRESENT bit in > DP_TRAINING_AUX_RD_INTERVAL register. If set, DPCD registers from > DP_DPCD_REV to DP_ADAPTER_CAP should be retrieved starting from > DP_DPCD_REV_EXTENDED. All registers are copied except DP_DPCD_REV, > DP_MAX_LINK_RATE and DP_DOWNSTREAMPORT_PRESENT which represent the > "true capabilities" of DPRX device. > > Original DP_DPCD_REV, DP_MAX_LINK_RATE and DP_DOWNSTREAMPORT_PRESENT > might falsely return lower capabilities to "avoid interoperability > issues with some of the existing DP Source devices that malfunction > when they discover the higher capabilities within those three > registers.". > > Before DP 1.4, DP_EXTENDED_RECEIVER_CAP_FIELD_PRESENT bit was reserved > and read 0 so it's safe to check against it even if DP revision is > <1.4 > > Signed-off-by: Quentin Schulz > Signed-off-by: Damian Kos in v4 you received a Reviewed-by: Manasi Navare for this patch. If a patch is largely unchanged from one version to another please add these previously received tags to the commit message. This prevents people from reviewing needlessly stuff twice ;-) . So the above should read ----- 8< ----- Signed-off-by: Quentin Schulz Signed-off-by: Damian Kos Reviewed-by: Manasi Navare ----- 8< ----- Heiko