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Message-ID: <CADnq5_NAOOsp6-NrnNc3cSTGM=yNXk8yddBPSxFawuONeAu-_Q@mail.gmail.com>
Date: Fri, 23 Mar 2012 15:34:00 -0400
From: Alex Deucher <alexdeucher@...il.com>
To: Lennert Buytenhek <buytenh@...tstofly.org>
Cc: linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org
Subject: Re: radeon + DVI->mDP converter + mDP display blank screen issue
since 3.0
On Fri, Mar 23, 2012 at 11:44 AM, Lennert Buytenhek
<buytenh@...tstofly.org> wrote:
> On Fri, Mar 23, 2012 at 10:59:27AM -0400, Alex Deucher wrote:
>
>> > Since Linux 3.0, a system with a Radeon HD 5450 (1002:68f9) connected
>> > to a 27" Apple LED cinema display via an Atlona AT-DP400 Dual Link DVI
>> > to Mini DisplayPort converter has started to stop giving screen
>> > output on switching from text mode to graphical framebuffer during
>> > system startup.
>> >
>> > I finally had some time to look at this, and it seems to have stopped
>> > working after this commit:
>> >
>> > commit df271bec805b42527d864777ed035fcbb42e76c0
>> > Author: Alex Deucher <alexdeucher@...il.com>
>> > Date: Fri May 20 04:34:15 2011 -0400
>> >
>> > drm/radeon/kms: properly handle bpc >8 in atom command tables
>> >
>> > Signed-off-by: Alex Deucher <alexdeucher@...il.com>
>> > Signed-off-by: Dave Airlie <airlied@...hat.com>
>> >
>> > ...and with the patch below (i.e. reverting part of the commit above)
>> > applied to 3.3 I get screen output again.
>> >
>> > Even though the monitor seems to have an 8 bit panel, it reports 10
>> > bits per channel in its EDID:
>> >
>> > [...]
>> > Manufacturer: APP Model 9226 Serial Number 41959462
>> > Made week 38 of 2010
>> > EDID version: 1.4
>> > Digital display
>> > 10 bits per primary color channel
>> > DisplayPort interface
>> > Maximum image size: 60 cm x 34 cm
>> > [...]
>> >
>> > The (active, dual link) DVI->mDP converter spec sheet says it supports
>> > 24 bit color, and I'm guessing that it can't deal with 30. Is the
>> > converter at fault here for passing through the EDID unchanged?
>> >
>> > Also, what would be the right way to handle this, a kernel command
>> > line or module option to limit color depth or something like that?
>> > ("Buy a video card with DP output." is a valid answer, I suppose.)
>> >
>> > I have no clue at all about graphics, and I have no idea whatsoever
>> > what I'm doing here, but I just wanted to post this somewhere for
>> > Google to find in case someone else runs into this!
>>
>> I've inquired with out display team on how to best handle this. In
>> the meantime, it's probably best to just default to 8 bpc. Does the
>> attached patch fix your issue?
>
> I've been using the patch below in a custom Fedora 17 kernel RPM, and
> that seems to fix the issue. Your patch seems to be a superset of
> this patch, so logically, your patch should do the trick as well. :)
Can you try the attached patch on top of my previous one?
Alex
>
>
> thanks,
> Lennert
>
>
> diff -up linux-3.3.0-1.fc17.x86_64/drivers/gpu/drm/radeon/atombios_crtc.c.orig linux-3.3.0-1.fc17.x86_64/drivers/gpu/drm/radeon/atombios_crtc.c
> --- linux-3.3.0-1.fc17.x86_64/drivers/gpu/drm/radeon/atombios_crtc.c.orig 2012-03-22 14:52:20.538854547 +0100
> +++ linux-3.3.0-1.fc17.x86_64/drivers/gpu/drm/radeon/atombios_crtc.c 2012-03-22 14:55:39.740794113 +0100
> @@ -550,8 +550,6 @@ static u32 atombios_adjust_pll(struct dr
> if (encoder->crtc == crtc) {
> radeon_encoder = to_radeon_encoder(encoder);
> connector = radeon_get_connector_for_encoder(encoder);
> - if (connector && connector->display_info.bpc)
> - bpc = connector->display_info.bpc;
> encoder_mode = atombios_get_encoder_mode(encoder);
> is_duallink = radeon_dig_monitor_is_duallink(encoder, mode->clock);
> if ((radeon_encoder->devices & (ATOM_DEVICE_LCD_SUPPORT | ATOM_DEVICE_DFP_SUPPORT)) ||
> @@ -922,7 +920,6 @@ static void atombios_crtc_set_pll(struct
> struct radeon_connector_atom_dig *dig_connector =
> radeon_connector->con_priv;
> int dp_clock;
> - bpc = connector->display_info.bpc;
>
> switch (encoder_mode) {
> case ATOM_ENCODER_MODE_DP_MST:
>
>
>
>> From 22ca454eb749968f266d6788a5f4778acc08cc66 Mon Sep 17 00:00:00 2001
>> From: Alex Deucher <alexander.deucher@....com>
>> Date: Fri, 23 Mar 2012 10:54:45 -0400
>> Subject: [PATCH] drm/radeon/kms/atom: force bpc to 8 for now
>>
>> Using the bpc (bits per color) specified by the monitor
>> can cause problems in some cases. Until we get a better
>> handle on how to deal with those cases, just use a bpc of 8.
>>
>> Reported-by: Lennert Buytenhek <buytenh@...tstofly.org>
>> Signed-off-by: Alex Deucher <alexander.deucher@....com>
>> Cc: stable@...nel.org
>> ---
>> drivers/gpu/drm/radeon/atombios_crtc.c | 8 +++++---
>> drivers/gpu/drm/radeon/atombios_dp.c | 3 +++
>> drivers/gpu/drm/radeon/atombios_encoders.c | 4 ++--
>> 3 files changed, 10 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/radeon/atombios_crtc.c b/drivers/gpu/drm/radeon/atombios_crtc.c
>> index 083b3ea..b5ff1f7 100644
>> --- a/drivers/gpu/drm/radeon/atombios_crtc.c
>> +++ b/drivers/gpu/drm/radeon/atombios_crtc.c
>> @@ -588,8 +588,8 @@ static u32 atombios_adjust_pll(struct drm_crtc *crtc,
>> if (encoder->crtc == crtc) {
>> radeon_encoder = to_radeon_encoder(encoder);
>> connector = radeon_get_connector_for_encoder(encoder);
>> - if (connector && connector->display_info.bpc)
>> - bpc = connector->display_info.bpc;
>> + /* if (connector && connector->display_info.bpc)
>> + bpc = connector->display_info.bpc; */
>> encoder_mode = atombios_get_encoder_mode(encoder);
>> is_duallink = radeon_dig_monitor_is_duallink(encoder, mode->clock);
>> if ((radeon_encoder->devices & (ATOM_DEVICE_LCD_SUPPORT | ATOM_DEVICE_DFP_SUPPORT)) ||
>> @@ -965,7 +965,9 @@ static void atombios_crtc_set_pll(struct drm_crtc *crtc, struct drm_display_mode
>> struct radeon_connector_atom_dig *dig_connector =
>> radeon_connector->con_priv;
>> int dp_clock;
>> - bpc = connector->display_info.bpc;
>> +
>> + /* if (connector->display_info.bpc)
>> + bpc = connector->display_info.bpc; */
>>
>> switch (encoder_mode) {
>> case ATOM_ENCODER_MODE_DP_MST:
>> diff --git a/drivers/gpu/drm/radeon/atombios_dp.c b/drivers/gpu/drm/radeon/atombios_dp.c
>> index 6c62be2..c57d856 100644
>> --- a/drivers/gpu/drm/radeon/atombios_dp.c
>> +++ b/drivers/gpu/drm/radeon/atombios_dp.c
>> @@ -405,10 +405,13 @@ static void dp_get_adjust_train(u8 link_status[DP_LINK_STATUS_SIZE],
>> /* get bpc from the EDID */
>> static int convert_bpc_to_bpp(int bpc)
>> {
>> +#if 0
>> if (bpc == 0)
>> return 24;
>> else
>> return bpc * 3;
>> +#endif
>> + return 24;
>> }
>>
>> /* get the max pix clock supported by the link rate and lane num */
>> diff --git a/drivers/gpu/drm/radeon/atombios_encoders.c b/drivers/gpu/drm/radeon/atombios_encoders.c
>> index 468b874..e607c4d 100644
>> --- a/drivers/gpu/drm/radeon/atombios_encoders.c
>> +++ b/drivers/gpu/drm/radeon/atombios_encoders.c
>> @@ -541,7 +541,7 @@ atombios_dig_encoder_setup(struct drm_encoder *encoder, int action, int panel_mo
>> dp_clock = dig_connector->dp_clock;
>> dp_lane_count = dig_connector->dp_lane_count;
>> hpd_id = radeon_connector->hpd.hpd;
>> - bpc = connector->display_info.bpc;
>> + /* bpc = connector->display_info.bpc; */
>> }
>>
>> /* no dig encoder assigned */
>> @@ -1159,7 +1159,7 @@ atombios_external_encoder_setup(struct drm_encoder *encoder,
>> dp_lane_count = dig_connector->dp_lane_count;
>> connector_object_id =
>> (radeon_connector->connector_object_id & OBJECT_ID_MASK) >> OBJECT_ID_SHIFT;
>> - bpc = connector->display_info.bpc;
>> + /* bpc = connector->display_info.bpc; */
>> }
>>
>> memset(&args, 0, sizeof(args));
>> --
>> 1.7.7.5
>>
View attachment "0001-drm-radeon-kms-improve-bpc-handling.patch" of type "text/x-patch" (6940 bytes)
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