From: Dave Stevenson <dave.stevenson@raspberrypi.com> To: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Cc: Chris Morgan <macromorgan@hotmail.com>, Emma Anholt <emma@anholt.net>, David Airlie <airlied@linux.ie>, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, Eric Anholt <eric@anholt.net>, Joerg Quinten <aBUGSworstnightmare@gmail.com>, Maxime Ripard <maxime@cerno.tech> Subject: Re: [PATCH 6/7] drm/vc4: dpi: Change the default DPI format to being 18bpp, not 24. Date: Mon, 17 Oct 2022 18:03:03 +0100 [thread overview] Message-ID: <CAPY8ntAiX6WJ86wGUgMvTxhehG8OgoS66AojvWYukADciM5X5w@mail.gmail.com> (raw) In-Reply-To: <Y0rqQu8Ztowj3/Gi@pendragon.ideasonboard.com> Hi Laurent On Sat, 15 Oct 2022 at 18:14, Laurent Pinchart <laurent.pinchart@ideasonboard.com> wrote: > > Hi Maxime (and Dave), > > Thank you for the patch. > > On Thu, Oct 13, 2022 at 11:56:50AM +0200, Maxime Ripard wrote: > > From: Dave Stevenson <dave.stevenson@raspberrypi.com> > > > > DPI hasn't really been used up until now, so the default has > > been meaningless. > > In theory we should be able to pass the desired format for the > > adjacent bridge chip through, but framework seems to be missing > > for that. > > Doesn't the bridge infrastructure allow that ? Or maybe this commit > message was written a while ago, before it was possible ? Infrastructure may do, but it isn't always implemented. Rightly or wrongly, the driver is currently finding the associated connector, as commented as [1]. The main chain I'm looking is: vc4_dpi -> dumb-vga-dac -> vga-connector Unless I'm missing something, nothing in that chain defines the format for the output. vga-connector (display-connector driver) tries to ask the previous bridge for formats via atomic_get_output_bus_fmts and atomic_get_input_fmts, but dumb-vga-dac (simple-bridge) doesn't implement them. So even if we tried following the chain it dies due to , and currently the connector has no bus_formats defined in display_info, hence we end up needing a default. (Why do I get deja vu with panel-dpi and bus-format discussions?!) Panels are fine as they do generally have a bus_format defined in display_info. [1] https://github.com/torvalds/linux/blob/master/drivers/gpu/drm/vc4/vc4_dpi.c#L139 > In any case, it would be nice to use the bus format exposed by the next > bridge in the chain, but that can be done in a subsequent step. The new > default seems reasonable. I'll add having a look at atomic_get_output_bus_fmts and atomic_get_input_fmts to my list of tasks again. Dave > Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> > > > As the main device to use DPI is the VGA666 or Adafruit Kippah, > > both of which use RGB666, change the default to being RGB666 instead > > of RGB888. > > > > Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com> > > Signed-off-by: Maxime Ripard <maxime@cerno.tech> > > --- > > drivers/gpu/drm/vc4/vc4_dpi.c | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/gpu/drm/vc4/vc4_dpi.c b/drivers/gpu/drm/vc4/vc4_dpi.c > > index ecbe4cd87036..fdae02760b6d 100644 > > --- a/drivers/gpu/drm/vc4/vc4_dpi.c > > +++ b/drivers/gpu/drm/vc4/vc4_dpi.c > > @@ -150,8 +150,8 @@ static void vc4_dpi_encoder_enable(struct drm_encoder *encoder) > > } > > drm_connector_list_iter_end(&conn_iter); > > > > - /* Default to 24bit if no connector or format found. */ > > - dpi_c |= VC4_SET_FIELD(DPI_FORMAT_24BIT_888_RGB, DPI_FORMAT); > > + /* Default to 18bit if no connector or format found. */ > > + dpi_c |= VC4_SET_FIELD(DPI_FORMAT_18BIT_666_RGB_1, DPI_FORMAT); > > > > if (connector) { > > if (connector->display_info.num_bus_formats) { > > > > -- > Regards, > > Laurent Pinchart
WARNING: multiple messages have this Message-ID (diff)
From: Dave Stevenson <dave.stevenson@raspberrypi.com> To: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Cc: Maxime Ripard <maxime@cerno.tech>, Maxime Ripard <mripard@kernel.org>, Eric Anholt <eric@anholt.net>, Daniel Vetter <daniel@ffwll.ch>, David Airlie <airlied@linux.ie>, Rob Herring <robh@kernel.org>, Emma Anholt <emma@anholt.net>, dri-devel@lists.freedesktop.org, Joerg Quinten <aBUGSworstnightmare@gmail.com>, Chris Morgan <macromorgan@hotmail.com>, linux-kernel@vger.kernel.org Subject: Re: [PATCH 6/7] drm/vc4: dpi: Change the default DPI format to being 18bpp, not 24. Date: Mon, 17 Oct 2022 18:03:03 +0100 [thread overview] Message-ID: <CAPY8ntAiX6WJ86wGUgMvTxhehG8OgoS66AojvWYukADciM5X5w@mail.gmail.com> (raw) In-Reply-To: <Y0rqQu8Ztowj3/Gi@pendragon.ideasonboard.com> Hi Laurent On Sat, 15 Oct 2022 at 18:14, Laurent Pinchart <laurent.pinchart@ideasonboard.com> wrote: > > Hi Maxime (and Dave), > > Thank you for the patch. > > On Thu, Oct 13, 2022 at 11:56:50AM +0200, Maxime Ripard wrote: > > From: Dave Stevenson <dave.stevenson@raspberrypi.com> > > > > DPI hasn't really been used up until now, so the default has > > been meaningless. > > In theory we should be able to pass the desired format for the > > adjacent bridge chip through, but framework seems to be missing > > for that. > > Doesn't the bridge infrastructure allow that ? Or maybe this commit > message was written a while ago, before it was possible ? Infrastructure may do, but it isn't always implemented. Rightly or wrongly, the driver is currently finding the associated connector, as commented as [1]. The main chain I'm looking is: vc4_dpi -> dumb-vga-dac -> vga-connector Unless I'm missing something, nothing in that chain defines the format for the output. vga-connector (display-connector driver) tries to ask the previous bridge for formats via atomic_get_output_bus_fmts and atomic_get_input_fmts, but dumb-vga-dac (simple-bridge) doesn't implement them. So even if we tried following the chain it dies due to , and currently the connector has no bus_formats defined in display_info, hence we end up needing a default. (Why do I get deja vu with panel-dpi and bus-format discussions?!) Panels are fine as they do generally have a bus_format defined in display_info. [1] https://github.com/torvalds/linux/blob/master/drivers/gpu/drm/vc4/vc4_dpi.c#L139 > In any case, it would be nice to use the bus format exposed by the next > bridge in the chain, but that can be done in a subsequent step. The new > default seems reasonable. I'll add having a look at atomic_get_output_bus_fmts and atomic_get_input_fmts to my list of tasks again. Dave > Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> > > > As the main device to use DPI is the VGA666 or Adafruit Kippah, > > both of which use RGB666, change the default to being RGB666 instead > > of RGB888. > > > > Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com> > > Signed-off-by: Maxime Ripard <maxime@cerno.tech> > > --- > > drivers/gpu/drm/vc4/vc4_dpi.c | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/gpu/drm/vc4/vc4_dpi.c b/drivers/gpu/drm/vc4/vc4_dpi.c > > index ecbe4cd87036..fdae02760b6d 100644 > > --- a/drivers/gpu/drm/vc4/vc4_dpi.c > > +++ b/drivers/gpu/drm/vc4/vc4_dpi.c > > @@ -150,8 +150,8 @@ static void vc4_dpi_encoder_enable(struct drm_encoder *encoder) > > } > > drm_connector_list_iter_end(&conn_iter); > > > > - /* Default to 24bit if no connector or format found. */ > > - dpi_c |= VC4_SET_FIELD(DPI_FORMAT_24BIT_888_RGB, DPI_FORMAT); > > + /* Default to 18bit if no connector or format found. */ > > + dpi_c |= VC4_SET_FIELD(DPI_FORMAT_18BIT_666_RGB_1, DPI_FORMAT); > > > > if (connector) { > > if (connector->display_info.num_bus_formats) { > > > > -- > Regards, > > Laurent Pinchart
next prev parent reply other threads:[~2022-10-17 17:03 UTC|newest] Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-10-13 9:56 [PATCH 0/7] drm/vc4: dpi: Various improvements Maxime Ripard 2022-10-13 9:56 ` Maxime Ripard 2022-10-13 9:56 ` [PATCH 1/7] media: uapi: add MEDIA_BUS_FMT_RGB565_1X24_CPADHI Maxime Ripard 2022-10-13 9:56 ` Maxime Ripard 2022-10-13 9:56 ` [PATCH 2/7] media: uapi: add MEDIA_BUS_FMT_BGR666_1X18 Maxime Ripard 2022-10-13 9:56 ` Maxime Ripard 2022-10-15 17:07 ` Laurent Pinchart 2022-10-15 17:07 ` Laurent Pinchart 2022-10-13 9:56 ` [PATCH 3/7] media: uapi: add MEDIA_BUS_FMT_BGR666_1X24_CPADHI Maxime Ripard 2022-10-13 9:56 ` Maxime Ripard 2022-10-13 9:56 ` [PATCH 4/7] drm/vc4: dpi: Support RGB565 format Maxime Ripard 2022-10-13 9:56 ` Maxime Ripard 2022-10-15 17:29 ` Laurent Pinchart 2022-10-15 17:29 ` Laurent Pinchart 2022-10-17 17:12 ` Dave Stevenson 2022-10-17 17:12 ` Dave Stevenson 2022-10-13 9:56 ` [PATCH 5/7] drm/vc4: dpi: Support BGR666 formats Maxime Ripard 2022-10-13 9:56 ` Maxime Ripard 2022-10-15 17:26 ` Laurent Pinchart 2022-10-15 17:26 ` Laurent Pinchart 2022-10-15 17:30 ` Laurent Pinchart 2022-10-15 17:30 ` Laurent Pinchart 2022-10-17 17:26 ` Dave Stevenson 2022-10-17 17:26 ` Dave Stevenson 2022-10-13 9:56 ` [PATCH 6/7] drm/vc4: dpi: Change the default DPI format to being 18bpp, not 24 Maxime Ripard 2022-10-13 9:56 ` Maxime Ripard 2022-10-15 17:13 ` Laurent Pinchart 2022-10-15 17:13 ` Laurent Pinchart 2022-10-17 17:03 ` Dave Stevenson [this message] 2022-10-17 17:03 ` Dave Stevenson 2022-10-13 9:56 ` [PATCH 7/7] drm/vc4: dpi: Fix format mapping for RGB565 Maxime Ripard 2022-10-13 9:56 ` Maxime Ripard 2022-10-15 17:19 ` Laurent Pinchart 2022-10-15 17:19 ` Laurent Pinchart
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