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Message-ID: <a010d333-70b1-bc58-ddf8-d3fa911a6852@ti.com>
Date: Wed, 3 Aug 2022 12:15:12 +0530
From: Aradhya Bhatia <a-bhatia1@...com>
To: Max Krummenacher <max.oss.09@...il.com>,
<max.krummenacher@...adex.com>
CC: Laurent Pinchart <laurent.pinchart@...asonboard.com>,
Rob Herring <robh@...nel.org>,
Dave Stevenson <dave.stevenson@...pberrypi.com>,
Maxime Ripard <mripard@...nel.org>,
Marek Vasut <marex@...x.de>,
Christoph Niedermaier <cniedermaier@...electronics.com>,
Francesco Dolcini <francesco.dolcini@...adex.com>,
Daniel Vetter <daniel@...ll.ch>,
David Airlie <airlied@...ux.ie>,
Sam Ravnborg <sam@...nborg.org>,
Thierry Reding <thierry.reding@...il.com>,
<dri-devel@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 4/4] drm/panel: simple: add bus-format support for
panel-dpi
On 28-Jun-22 23:48, Max Krummenacher wrote:
> From: Max Krummenacher <max.krummenacher@...adex.com>
>
> Evaluate the device tree bus-format property to set bus_format for
> a 'panel-dpi' panel. Additionally infer the bpc value from the
> given bus-format.
>
> Valid values for bus-format are found in:
> <include/dt-bindings/display/dt-media-bus-format.h>
>
> This completes the addition of panel-dpi to completely specify
> a panel-simple panel from the device tree.
>
> Signed-off-by: Max Krummenacher <max.krummenacher@...adex.com>
>
> ---
>
> Changes in v3:
> - Moved the bus-format property under the port/endpoint node as
> suggested by Rob Herring
>
> Changes in v2:
> - Fix errors found by dt_binding_check
>
> drivers/gpu/drm/panel/panel-simple.c | 49 ++++++++++++++++++++++++++++
> 1 file changed, 49 insertions(+)
>
> diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c
> index 4a2e580a2f7b..f1a457f1069e 100644
> --- a/drivers/gpu/drm/panel/panel-simple.c
> +++ b/drivers/gpu/drm/panel/panel-simple.c
> @@ -21,9 +21,11 @@
> * DEALINGS IN THE SOFTWARE.
> */
>
> +#include <dt-bindings/display/dt-media-bus-format.h>
> #include <linux/delay.h>
> #include <linux/gpio/consumer.h>
> #include <linux/module.h>
> +#include <linux/of_graph.h>
> #include <linux/of_platform.h>
> #include <linux/platform_device.h>
> #include <linux/pm_runtime.h>
> @@ -449,10 +451,12 @@ static int panel_dpi_probe(struct device *dev,
> struct panel_simple *panel)
> {
> struct display_timing *timing;
> + struct device_node *endpoint;
> const struct device_node *np;
> struct panel_desc *desc;
> unsigned int bus_flags;
> struct videomode vm;
> + u32 bus_format;
> int ret;
>
> np = dev->of_node;
> @@ -477,6 +481,51 @@ static int panel_dpi_probe(struct device *dev,
> of_property_read_u32(np, "width-mm", &desc->size.width);
> of_property_read_u32(np, "height-mm", &desc->size.height);
>
> + endpoint = of_graph_get_endpoint_by_regs(np, -1, -1);
> + if (endpoint &&
> + !of_property_read_u32(endpoint, "bus-format", &bus_format)) {
> + /* infer bpc from bus-format */
> + switch (bus_format) {
> + case DT_MEDIA_BUS_FMT_RGB565_1X16:
> + desc->bus_format = MEDIA_BUS_FMT_RGB565_1X16;
> + desc->bpc = 6;
> + break;
> + case DT_MEDIA_BUS_FMT_RGB666_1X18:
> + desc->bus_format = MEDIA_BUS_FMT_RGB666_1X18;
> + desc->bpc = 6;
> + break;
> + case DT_MEDIA_BUS_FMT_RGB666_1X24_CPADHI:
> + desc->bus_format = MEDIA_BUS_FMT_RGB666_1X24_CPADHI;
> + desc->bpc = 6;
> + break;
> + case DT_MEDIA_BUS_FMT_BGR888_1X24:
> + desc->bus_format = MEDIA_BUS_FMT_BGR888_1X24;
> + desc->bpc = 8;
> + break;
> + case DT_MEDIA_BUS_FMT_GBR888_1X24:
> + desc->bus_format = MEDIA_BUS_FMT_GBR888_1X24;
> + desc->bpc = 8;
> + break;
> + case DT_MEDIA_BUS_FMT_RBG888_1X24:
> + desc->bus_format = MEDIA_BUS_FMT_RBG888_1X24;
> + desc->bpc = 8;
> + break;
> + case DT_MEDIA_BUS_FMT_RGB888_1X24:
> + desc->bus_format = MEDIA_BUS_FMT_RGB888_1X24;
> + desc->bpc = 8;
> + break;
> + case DT_MEDIA_BUS_FMT_RGB888_1X32_PADHI:
> + desc->bus_format = MEDIA_BUS_FMT_RGB888_1X32_PADHI;
> + desc->bpc = 8;
> + break;
> + default:
> + dev_err(dev, "%pOF: unknown bus-format property\n", np);
> + return -EINVAL;
> + }
> + }
> +
> + of_node_put(endpoint);
> +
> /* Extract bus_flags from display_timing */
> bus_flags = 0;
> vm.flags = timing->flags;
I understand that it is important to add a bus-format property for dumb
dpi-panels, and I agree with the implementation in the patch-set.
However,
I do not yet fully understand Rob's comments on the dt-bindings side of
patch set (patch 1/4) and what consequences it may cause if that remains
unresolved.
Given that the bus-format property gets added, I do not see any concern
with the panel-simple driver patch.
Reviewed-by: Aradhya Bhatia <a-bhatia1@...com>
Regards
Aradhya
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