From mboxrd@z Thu Jan 1 00:00:00 1970 From: Todd Previte Subject: Re: [PATCH 12/12] drm/i915: Add a delay in Displayport AUX transactions for compliance testing Date: Tue, 15 Jul 2014 08:34:18 -0700 Message-ID: <53C549FA.4050102@gmail.com> References: <1405365047-6866-1-git-send-email-tprevite@gmail.com> <1405365047-6866-13-git-send-email-tprevite@gmail.com> <20140715074628.GO15237@phenom.ffwll.local> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============0167890971==" Return-path: Received: from mail-pd0-f173.google.com (mail-pd0-f173.google.com [209.85.192.173]) by gabe.freedesktop.org (Postfix) with ESMTP id 1843B6E5B1 for ; Tue, 15 Jul 2014 08:34:19 -0700 (PDT) Received: by mail-pd0-f173.google.com with SMTP id w10so29592pde.4 for ; Tue, 15 Jul 2014 08:34:18 -0700 (PDT) In-Reply-To: <20140715074628.GO15237@phenom.ffwll.local> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" To: Daniel Vetter Cc: intel-gfx@lists.freedesktop.org List-Id: intel-gfx@lists.freedesktop.org This is a multi-part message in MIME format. --===============0167890971== Content-Type: multipart/alternative; boundary="------------050106050707010705020200" This is a multi-part message in MIME format. --------------050106050707010705020200 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit > Daniel Vetter > Tuesday, July 15, 2014 12:46 AM > On Mon, Jul 14, 2014 at 12:10:47PM -0700, Todd Previte wrote: >> The Displayport Link Layer Compliance Testing Specification 1.2 rev 1.1 specifies that >> repeated AUX transactions after a failure (NACK, DEFER or no response) must have >> a minimum delay of 400us before the resend can occur. Tests 4.2.1.1 and 4.2.1.2 are two >> tests that require this specifically. >> >> Signed-off-by: Todd Previte > > Since this is a minimal timeout ... shouldn't we put it into the dp > helpers instead? > -Daniel This delay catches the case where the sink device either does not respond at all or responds with an invalid AUX transaction. These are lower level errors than the DRM helper functions are supposed to handle. I mistakenly mentioned NACK/DEFER in the commit message - that's not an accurate description of what this patch does. I will fix the commit message for v3 of this patch. -T >> --- >> drivers/gpu/drm/i915/intel_dp.c | 6 +++++- >> 1 file changed, 5 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c >> index 0e207aaf..f0664cd 100644 >> --- a/drivers/gpu/drm/i915/intel_dp.c >> +++ b/drivers/gpu/drm/i915/intel_dp.c >> @@ -573,8 +573,12 @@ intel_dp_aux_ch(struct intel_dp *intel_dp, >> DP_AUX_CH_CTL_RECEIVE_ERROR); >> >> if (status& (DP_AUX_CH_CTL_TIME_OUT_ERROR | >> - DP_AUX_CH_CTL_RECEIVE_ERROR)) >> + DP_AUX_CH_CTL_RECEIVE_ERROR)) { >> + /* DP compliance requires 400us delay for errors/timeouts >> + (DP CTS 1.2 Core Rev 1.1, 4.2.1.1& 4.2.1.2) */ >> + udelay(400); >> continue; >> + } >> if (status& DP_AUX_CH_CTL_DONE) >> break; >> } >> -- >> 1.9.1 >> >> _______________________________________________ >> Intel-gfx mailing list >> Intel-gfx@lists.freedesktop.org >> http://lists.freedesktop.org/mailman/listinfo/intel-gfx > > Todd Previte > Monday, July 14, 2014 12:10 PM > The Displayport Link Layer Compliance Testing Specification 1.2 rev > 1.1 specifies that > repeated AUX transactions after a failure (NACK, DEFER or no response) > must have > a minimum delay of 400us before the resend can occur. Tests 4.2.1.1 > and 4.2.1.2 are two > tests that require this specifically. > > Signed-off-by: Todd Previte > --- > drivers/gpu/drm/i915/intel_dp.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/i915/intel_dp.c > b/drivers/gpu/drm/i915/intel_dp.c > index 0e207aaf..f0664cd 100644 > --- a/drivers/gpu/drm/i915/intel_dp.c > +++ b/drivers/gpu/drm/i915/intel_dp.c > @@ -573,8 +573,12 @@ intel_dp_aux_ch(struct intel_dp *intel_dp, > DP_AUX_CH_CTL_RECEIVE_ERROR); > > if (status & (DP_AUX_CH_CTL_TIME_OUT_ERROR | > - DP_AUX_CH_CTL_RECEIVE_ERROR)) > + DP_AUX_CH_CTL_RECEIVE_ERROR)) { > + /* DP compliance requires 400us delay for errors/timeouts > + (DP CTS 1.2 Core Rev 1.1, 4.2.1.1 & 4.2.1.2) */ > + udelay(400); > continue; > + } > if (status & DP_AUX_CH_CTL_DONE) > break; > } > Todd Previte > Monday, July 14, 2014 12:10 PM > > V2: > - Addressed review feedback from the mailing list > - Broke up patches into smaller, easily managed chunks > - Reordered the patches such that they can be applied in order > - Fixed checkpatch.pl errors across the patchset > - Updated and enhanced functionality for the EDID test function > - Completely revamped the mode set operations for compliance testing > -- Sent with Postbox --------------050106050707010705020200 Content-Type: multipart/related; boundary="------------070108090105030901040309" --------------070108090105030901040309 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit
Tuesday, July 15, 2014 12:46 AM
On Mon, Jul 14, 2014 at 12:10:47PM -0700, Todd Previte wrote:

The Displayport Link Layer Compliance Testing Specification 1.2 rev 1.1 specifies that
repeated AUX transactions after a failure (NACK, DEFER or no response) must have
a minimum delay of 400us before the resend can occur. Tests 4.2.1.1 and 4.2.1.2 are two
tests that require this specifically.

Signed-off-by: Todd Previte <tprevite@gmail.com>


Since this is a minimal timeout ... shouldn't we put it into the dp
helpers instead?
-Daniel
This delay catches the case where the sink device either does not respond at all or responds with an invalid AUX transaction. These are lower level errors than the DRM helper functions are supposed to handle. I mistakenly mentioned NACK/DEFER in the commit message - that's not an accurate description of what this patch does. I will fix the commit message for v3 of this patch.


-T
---
 drivers/gpu/drm/i915/intel_dp.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 0e207aaf..f0664cd 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -573,8 +573,12 @@ intel_dp_aux_ch(struct intel_dp *intel_dp,
 				   DP_AUX_CH_CTL_RECEIVE_ERROR);
 
 			if (status & (DP_AUX_CH_CTL_TIME_OUT_ERROR |
-				      DP_AUX_CH_CTL_RECEIVE_ERROR))
+				      DP_AUX_CH_CTL_RECEIVE_ERROR)) {
+				/* DP compliance requires 400us delay for errors/timeouts
+				   (DP CTS 1.2 Core Rev 1.1, 4.2.1.1 & 4.2.1.2) */
+				udelay(400);
 				continue;
+			}
 			if (status & DP_AUX_CH_CTL_DONE)
 				break;
 		}
-- 
1.9.1

_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
http://lists.freedesktop.org/mailman/listinfo/intel-gfx
Monday, July 14, 2014 12:10 PM
The Displayport Link Layer Compliance Testing Specification 1.2 rev 1.1 specifies that
repeated AUX transactions after a failure (NACK, DEFER or no response) must have
a minimum delay of 400us before the resend can occur. Tests 4.2.1.1 and 4.2.1.2 are two
tests that require this specifically.

Signed-off-by: Todd Previte <tprevite@gmail.com>
---
drivers/gpu/drm/i915/intel_dp.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 0e207aaf..f0664cd 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -573,8 +573,12 @@ intel_dp_aux_ch(struct intel_dp *intel_dp,
DP_AUX_CH_CTL_RECEIVE_ERROR);

if (status & (DP_AUX_CH_CTL_TIME_OUT_ERROR |
- DP_AUX_CH_CTL_RECEIVE_ERROR))
+ DP_AUX_CH_CTL_RECEIVE_ERROR)) {
+ /* DP compliance requires 400us delay for errors/timeouts
+ (DP CTS 1.2 Core Rev 1.1, 4.2.1.1 & 4.2.1.2) */
+ udelay(400);
continue;
+ }
if (status & DP_AUX_CH_CTL_DONE)
break;
}
Monday, July 14, 2014 12:10 PM

V2:
- Addressed review feedback from the mailing list
- Broke up patches into smaller, easily managed chunks
- Reordered the patches such that they can be applied in order
- Fixed checkpatch.pl errors across the patchset
- Updated and enhanced functionality for the EDID test function
- Completely revamped the mode set operations for compliance testing


--
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