From: "Ville Syrjälä" <ville.syrjala@linux.intel.com> To: Lyude <cpaul@redhat.com> Cc: dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, David Airlie <airlied@linux.ie>, open list <linux-kernel@vger.kernel.org> Subject: Re: [PATCH v6 3/4] drm/dp_helper: Perform throw-away read before actual read in drm_dp_dpcd_read() Date: Fri, 15 Apr 2016 17:31:02 +0300 [thread overview] Message-ID: <20160415143102.GW4329@intel.com> (raw) In-Reply-To: <1460730335-5012-1-git-send-email-cpaul@redhat.com> On Fri, Apr 15, 2016 at 10:25:35AM -0400, Lyude wrote: > This is part of a patch series to migrate all of the workarounds for > commonly seen behavior from bad sinks in intel_dp_dpcd_read_wake() to drm's > DP helper. > > Some sinks will just return garbage for the first aux tranaction they > receive when coming out of sleep mode, so we need to perform an additional > read before the actual read to workaround this. > > Changes since v5 > - If the throwaway read in drm_dp_dpcd_read() fails, return the error > from that instead of continuing. This follows the same logic we do in > drm_dp_dpcd_access() (e.g. the error from the first transaction may > differ from the errors that proceeding attempts might return). > > Signed-off-by: Lyude <cpaul@redhat.com> Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Tested-by: Ville Syrjälä <ville.syrjala@linux.intel.com> > --- > drivers/gpu/drm/drm_dp_helper.c | 19 +++++++++++++++++++ > 1 file changed, 19 insertions(+) > > diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c > index 540c3e4..eeaf5a7 100644 > --- a/drivers/gpu/drm/drm_dp_helper.c > +++ b/drivers/gpu/drm/drm_dp_helper.c > @@ -248,6 +248,25 @@ unlock: > ssize_t drm_dp_dpcd_read(struct drm_dp_aux *aux, unsigned int offset, > void *buffer, size_t size) > { > + int ret; > + > + /* > + * HP ZR24w corrupts the first DPCD access after entering power save > + * mode. Eg. on a read, the entire buffer will be filled with the same > + * byte. Do a throw away read to avoid corrupting anything we care > + * about. Afterwards things will work correctly until the monitor > + * gets woken up and subsequently re-enters power save mode. > + * > + * The user pressing any button on the monitor is enough to wake it > + * up, so there is no particularly good place to do the workaround. > + * We just have to do it before any DPCD access and hope that the > + * monitor doesn't power down exactly after the throw away read. > + */ > + ret = drm_dp_dpcd_access(aux, DP_AUX_NATIVE_READ, DP_DPCD_REV, buffer, > + 1); > + if (ret != 1) > + return ret; > + > return drm_dp_dpcd_access(aux, DP_AUX_NATIVE_READ, offset, buffer, > size); > } > -- > 2.5.5 -- Ville Syrjälä Intel OTC
WARNING: multiple messages have this Message-ID (diff)
From: "Ville Syrjälä" <ville.syrjala@linux.intel.com> To: Lyude <cpaul@redhat.com> Cc: intel-gfx@lists.freedesktop.org, open list <linux-kernel@vger.kernel.org>, dri-devel@lists.freedesktop.org Subject: Re: [PATCH v6 3/4] drm/dp_helper: Perform throw-away read before actual read in drm_dp_dpcd_read() Date: Fri, 15 Apr 2016 17:31:02 +0300 [thread overview] Message-ID: <20160415143102.GW4329@intel.com> (raw) In-Reply-To: <1460730335-5012-1-git-send-email-cpaul@redhat.com> On Fri, Apr 15, 2016 at 10:25:35AM -0400, Lyude wrote: > This is part of a patch series to migrate all of the workarounds for > commonly seen behavior from bad sinks in intel_dp_dpcd_read_wake() to drm's > DP helper. > > Some sinks will just return garbage for the first aux tranaction they > receive when coming out of sleep mode, so we need to perform an additional > read before the actual read to workaround this. > > Changes since v5 > - If the throwaway read in drm_dp_dpcd_read() fails, return the error > from that instead of continuing. This follows the same logic we do in > drm_dp_dpcd_access() (e.g. the error from the first transaction may > differ from the errors that proceeding attempts might return). > > Signed-off-by: Lyude <cpaul@redhat.com> Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Tested-by: Ville Syrjälä <ville.syrjala@linux.intel.com> > --- > drivers/gpu/drm/drm_dp_helper.c | 19 +++++++++++++++++++ > 1 file changed, 19 insertions(+) > > diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c > index 540c3e4..eeaf5a7 100644 > --- a/drivers/gpu/drm/drm_dp_helper.c > +++ b/drivers/gpu/drm/drm_dp_helper.c > @@ -248,6 +248,25 @@ unlock: > ssize_t drm_dp_dpcd_read(struct drm_dp_aux *aux, unsigned int offset, > void *buffer, size_t size) > { > + int ret; > + > + /* > + * HP ZR24w corrupts the first DPCD access after entering power save > + * mode. Eg. on a read, the entire buffer will be filled with the same > + * byte. Do a throw away read to avoid corrupting anything we care > + * about. Afterwards things will work correctly until the monitor > + * gets woken up and subsequently re-enters power save mode. > + * > + * The user pressing any button on the monitor is enough to wake it > + * up, so there is no particularly good place to do the workaround. > + * We just have to do it before any DPCD access and hope that the > + * monitor doesn't power down exactly after the throw away read. > + */ > + ret = drm_dp_dpcd_access(aux, DP_AUX_NATIVE_READ, DP_DPCD_REV, buffer, > + 1); > + if (ret != 1) > + return ret; > + > return drm_dp_dpcd_access(aux, DP_AUX_NATIVE_READ, offset, buffer, > size); > } > -- > 2.5.5 -- Ville Syrjälä Intel OTC _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
next prev parent reply other threads:[~2016-04-15 14:31 UTC|newest] Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-03-28 14:33 [PATCH v4 RESEND 0/5] Move workarounds from intel_dp_dpcd_read_wake() into drm's DP helpers Lyude 2016-03-28 14:33 ` Lyude 2016-03-28 14:31 ` ✗ Fi.CI.BAT: failure for " Patchwork 2016-03-28 14:33 ` [PATCH v4 RESEND 1/5] drm/dp_helper: Increase retry interval to 1000us Lyude 2016-03-28 14:33 ` Lyude 2016-03-29 8:27 ` Daniel Vetter 2016-03-29 8:27 ` Daniel Vetter 2016-03-29 14:05 ` Lyude Paul 2016-03-28 14:33 ` [PATCH v4 RESEND 2/5] drm/dp_helper: Always wait before retrying native aux transactions Lyude 2016-03-28 14:33 ` Lyude 2016-03-28 14:33 ` [PATCH v4 RESEND 3/5] drm/dp_helper: Retry aux transactions on all errors Lyude 2016-03-28 14:33 ` Lyude 2016-03-28 14:33 ` [PATCH v4 RESEND 4/5] drm/dp_helper: Perform throw-away read before actual read in drm_dp_dpcd_read() Lyude 2016-03-28 14:33 ` Lyude 2016-03-29 20:43 ` [PATCH v5 " Lyude 2016-03-29 20:43 ` Lyude 2016-03-28 14:33 ` [PATCH v4 RESEND 5/5] drm/i915: Get rid of intel_dp_dpcd_read_wake() Lyude 2016-03-28 14:33 ` Lyude 2016-03-30 14:26 ` Jani Nikula 2016-03-30 14:26 ` Jani Nikula 2016-04-12 10:17 ` [PATCH v4 RESEND 0/5] Move workarounds from intel_dp_dpcd_read_wake() into drm's DP helpers Jani Nikula 2016-04-12 10:17 ` Jani Nikula 2016-04-12 15:59 ` Lyude 2016-04-12 15:59 ` Lyude 2016-04-13 14:58 ` [PATCH v5 0/4] " Lyude 2016-04-13 14:58 ` Lyude 2016-04-13 14:58 ` [PATCH v5 1/4] drm/dp_helper: Always wait before retrying native aux transactions Lyude 2016-04-13 14:58 ` Lyude 2016-04-13 14:58 ` [PATCH v5 2/4] drm/dp_helper: Retry aux transactions on all errors Lyude 2016-04-13 14:58 ` Lyude 2016-04-13 14:58 ` [PATCH v5 3/4] drm/dp_helper: Perform throw-away read before actual read in drm_dp_dpcd_read() Lyude 2016-04-13 14:58 ` Lyude 2016-04-14 17:01 ` Ville Syrjälä 2016-04-14 17:01 ` Ville Syrjälä 2016-04-15 14:25 ` [PATCH v6 " Lyude 2016-04-15 14:25 ` Lyude 2016-04-15 14:31 ` Ville Syrjälä [this message] 2016-04-15 14:31 ` Ville Syrjälä 2016-04-13 14:58 ` [PATCH v5 4/4] drm/i915: Get rid of intel_dp_dpcd_read_wake() Lyude 2016-04-13 14:58 ` Lyude 2016-04-22 16:54 ` Daniel Vetter 2016-04-22 16:54 ` Daniel Vetter 2016-04-14 10:58 ` ✗ Fi.CI.BAT: failure for series starting with [v5,1/4] drm/dp_helper: Always wait before retrying native aux transactions Patchwork
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=20160415143102.GW4329@intel.com \ --to=ville.syrjala@linux.intel.com \ --cc=airlied@linux.ie \ --cc=cpaul@redhat.com \ --cc=dri-devel@lists.freedesktop.org \ --cc=intel-gfx@lists.freedesktop.org \ --cc=linux-kernel@vger.kernel.org \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.