RE: [PATCH v3 7/9] drm/atomic-helper: Add select_output_bus_format callback
Hi Maxime,
Thank you for the review.
> -Original Message-
> From: Maxime Ripard
> Sent: Friday, March 22, 2024 2:45 AM
> To: Klymenko, Anatoliy
> Cc: Laurent Pinchart ; Maarten Lankhorst
> ; Thomas Zimmermann
> ; David Airlie ; Daniel Vetter
> ; Simek, Michal ; Andrzej Hajda
> ; Neil Armstrong ; Robert
> Foss ; Jonas Karlman ; Jernej Skrabec
> ; Rob Herring ; Krzysztof
> Kozlowski ; Conor Dooley
> ; Mauro Carvalho Chehab ; Tomi
> Valkeinen ; dri-devel@lists.freedesktop.org;
> linux-arm-ker...@lists.infradead.org; linux-ker...@vger.kernel.org;
> devicet...@vger.kernel.org; linux-me...@vger.kernel.org
> Subject: Re: [PATCH v3 7/9] drm/atomic-helper: Add select_output_bus_format
> callback
>
> On Thu, Mar 21, 2024 at 01:43:45PM -0700, Anatoliy Klymenko wrote:
> > diff --git a/drivers/gpu/drm/drm_crtc_helper.c
> > b/drivers/gpu/drm/drm_crtc_helper.c
> > index 2dafc39a27cb..f2e12a3c4e5f 100644
> > --- a/drivers/gpu/drm/drm_crtc_helper.c
> > +++ b/drivers/gpu/drm/drm_crtc_helper.c
> > @@ -1055,3 +1055,39 @@ int drm_helper_force_disable_all(struct
> drm_device *dev)
> > return ret;
> > }
> > EXPORT_SYMBOL(drm_helper_force_disable_all);
> > +
> > +/**
> > + * drm_helper_crtc_select_output_bus_format - Select output media bus
> > +format
> > + * @crtc: The CRTC to query
> > + * @crtc_state: The new CRTC state
> > + * @supported_fmts: List of media bus format options to pick from
> > + * @num_supported_fmts: Number of media bus formats in
> > +@supported_fmts list
> > + *
> > + * Encoder drivers may call this helper to give the connected CRTC a
> > +chance to
> > + * select compatible or preffered media bus format to use over the
> > +CRTC encoder
> > + * link. Encoders should provide list of supported input
> > +MEDIA_BUS_FMT_* for
> > + * CRTC to pick from. CRTC driver is expected to select preferred
> > +media bus
> > + * format from the list and, once enabled, generate the signal accordingly.
> > + *
> > + * Returns:
> > + * Selected preferred media bus format or 0 if CRTC does not support
> > +any from
> > + * @supported_fmts list.
> > + */
> > +u32 drm_helper_crtc_select_output_bus_format(struct drm_crtc *crtc,
> > +struct drm_crtc_state *crtc_state,
> > +const u32 *supported_fmts,
> > +unsigned int num_supported_fmts) {
> > + if (!crtc || !supported_fmts || !num_supported_fmts)
> > + return 0;
> > +
> > + if (!crtc->helper_private ||
> > + !crtc->helper_private->select_output_bus_format)
> > + return supported_fmts[0];
> > +
> > + return crtc->helper_private->select_output_bus_format(crtc,
> > + crtc_state,
> > + supported_fmts,
> > + num_supported_fmts);
> > +}
>
> Again, the output of that selection must be found in the CRTC state, otherwise
> CRTCs have no way to know which have been selected.
>
Yes, now I got it - thank you. I'll fix this in the next version.
> Maxime
Thank you,
Anatoliy
Re: [PATCH v3 7/9] drm/atomic-helper: Add select_output_bus_format callback
On Thu, Mar 21, 2024 at 01:43:45PM -0700, Anatoliy Klymenko wrote:
> diff --git a/drivers/gpu/drm/drm_crtc_helper.c
> b/drivers/gpu/drm/drm_crtc_helper.c
> index 2dafc39a27cb..f2e12a3c4e5f 100644
> --- a/drivers/gpu/drm/drm_crtc_helper.c
> +++ b/drivers/gpu/drm/drm_crtc_helper.c
> @@ -1055,3 +1055,39 @@ int drm_helper_force_disable_all(struct drm_device
> *dev)
> return ret;
> }
> EXPORT_SYMBOL(drm_helper_force_disable_all);
> +
> +/**
> + * drm_helper_crtc_select_output_bus_format - Select output media bus format
> + * @crtc: The CRTC to query
> + * @crtc_state: The new CRTC state
> + * @supported_fmts: List of media bus format options to pick from
> + * @num_supported_fmts: Number of media bus formats in @supported_fmts list
> + *
> + * Encoder drivers may call this helper to give the connected CRTC a chance
> to
> + * select compatible or preffered media bus format to use over the CRTC
> encoder
> + * link. Encoders should provide list of supported input MEDIA_BUS_FMT_* for
> + * CRTC to pick from. CRTC driver is expected to select preferred media bus
> + * format from the list and, once enabled, generate the signal accordingly.
> + *
> + * Returns:
> + * Selected preferred media bus format or 0 if CRTC does not support any from
> + * @supported_fmts list.
> + */
> +u32 drm_helper_crtc_select_output_bus_format(struct drm_crtc *crtc,
> + struct drm_crtc_state *crtc_state,
> + const u32 *supported_fmts,
> + unsigned int num_supported_fmts)
> +{
> + if (!crtc || !supported_fmts || !num_supported_fmts)
> + return 0;
> +
> + if (!crtc->helper_private ||
> + !crtc->helper_private->select_output_bus_format)
> + return supported_fmts[0];
> +
> + return crtc->helper_private->select_output_bus_format(crtc,
> + crtc_state,
> + supported_fmts,
> + num_supported_fmts);
> +}
Again, the output of that selection must be found in the CRTC state,
otherwise CRTCs have no way to know which have been selected.
Maxime
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Description: PGP signature
[PATCH v3 7/9] drm/atomic-helper: Add select_output_bus_format callback
Add optional drm_crtc_helper_funcs.select_output_bus_format callback. This
callback allows to negotiate compatible media bus format on the link
between CRTC and connected DRM encoder or DRM bridge chain. A good usage
example is the CRTC implemented as FPGA soft IP. This kind of CRTC will
most certainly support a single output media bus format, as supporting
multiple runtime options consumes extra FPGA resources. A variety of
options for the FPGA designs are usually achieved by synthesizing IP with
different parameters.
Add drm_helper_crtc_select_output_bus_format that wraps
drm_crtc_helper_funcs.select_output_bus_format.
Incorporate select_output_bus_format callback into the format negotiation
stage to fix the input bus format of the first DRM bridge in the chain.
Signed-off-by: Anatoliy Klymenko
---
drivers/gpu/drm/drm_bridge.c | 14 +++--
drivers/gpu/drm/drm_crtc_helper.c| 36
include/drm/drm_crtc_helper.h| 5 +
include/drm/drm_modeset_helper_vtables.h | 30 ++
4 files changed, 83 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
index 521a71c61b16..955ca108cd4b 100644
--- a/drivers/gpu/drm/drm_bridge.c
+++ b/drivers/gpu/drm/drm_bridge.c
@@ -28,6 +28,7 @@
#include
#include
+#include
#include
#include
#include
@@ -879,7 +880,8 @@ static int select_bus_fmt_recursive(struct drm_bridge
*first_bridge,
unsigned int i, num_in_bus_fmts = 0;
struct drm_bridge_state *cur_state;
struct drm_bridge *prev_bridge;
- u32 *in_bus_fmts;
+ struct drm_crtc *crtc = crtc_state->crtc;
+ u32 *in_bus_fmts, in_fmt;
int ret;
prev_bridge = drm_bridge_get_prev_bridge(cur_bridge);
@@ -933,7 +935,15 @@ static int select_bus_fmt_recursive(struct drm_bridge
*first_bridge,
return -ENOMEM;
if (first_bridge == cur_bridge) {
- cur_state->input_bus_cfg.format = in_bus_fmts[0];
+ in_fmt = drm_helper_crtc_select_output_bus_format(crtc,
+ crtc_state,
+ in_bus_fmts,
+ num_in_bus_fmts);
+ if (!in_fmt) {
+ kfree(in_bus_fmts);
+ return -ENOTSUPP;
+ }
+ cur_state->input_bus_cfg.format = in_fmt;
cur_state->output_bus_cfg.format = out_bus_fmt;
kfree(in_bus_fmts);
return 0;
diff --git a/drivers/gpu/drm/drm_crtc_helper.c
b/drivers/gpu/drm/drm_crtc_helper.c
index 2dafc39a27cb..f2e12a3c4e5f 100644
--- a/drivers/gpu/drm/drm_crtc_helper.c
+++ b/drivers/gpu/drm/drm_crtc_helper.c
@@ -1055,3 +1055,39 @@ int drm_helper_force_disable_all(struct drm_device *dev)
return ret;
}
EXPORT_SYMBOL(drm_helper_force_disable_all);
+
+/**
+ * drm_helper_crtc_select_output_bus_format - Select output media bus format
+ * @crtc: The CRTC to query
+ * @crtc_state: The new CRTC state
+ * @supported_fmts: List of media bus format options to pick from
+ * @num_supported_fmts: Number of media bus formats in @supported_fmts list
+ *
+ * Encoder drivers may call this helper to give the connected CRTC a chance to
+ * select compatible or preffered media bus format to use over the CRTC encoder
+ * link. Encoders should provide list of supported input MEDIA_BUS_FMT_* for
+ * CRTC to pick from. CRTC driver is expected to select preferred media bus
+ * format from the list and, once enabled, generate the signal accordingly.
+ *
+ * Returns:
+ * Selected preferred media bus format or 0 if CRTC does not support any from
+ * @supported_fmts list.
+ */
+u32 drm_helper_crtc_select_output_bus_format(struct drm_crtc *crtc,
+struct drm_crtc_state *crtc_state,
+const u32 *supported_fmts,
+unsigned int num_supported_fmts)
+{
+ if (!crtc || !supported_fmts || !num_supported_fmts)
+ return 0;
+
+ if (!crtc->helper_private ||
+ !crtc->helper_private->select_output_bus_format)
+ return supported_fmts[0];
+
+ return crtc->helper_private->select_output_bus_format(crtc,
+ crtc_state,
+ supported_fmts,
+ num_supported_fmts);
+}
+EXPORT_SYMBOL(drm_helper_crtc_select_output_bus_format);
diff --git a/include/drm/drm_crtc_helper.h b/include/drm/drm_crtc_helper.h
index 8c886fc46ef2..b7eb52f3ce41 100644
--- a/include/drm/drm_crtc_helper.h
+++ b/include/drm/drm_crtc_helper.h
@@ -38,6 +38,7 @@
struct drm_atomic_state;
struct drm_connector;
struct drm_crtc;
+struct drm_crtc_state;
