Hello Laurent,
Thank you for your feedback!
> From: devicetree-ow...@vger.kernel.org <devicetree-ow...@vger.kernel.org> On
> Behalf Of Laurent Pinchart
> Sent: 07 November 2019 20:35
> Subject: Re: [PATCH v3 2/7] drm/bridge: Repurpose lvds-encoder.c
>
> Hi Fabrizio,
>
> Thank you for the patch.
>
> On Thu, Nov 07, 2019 at 08:10:58PM +0000, Fabrizio Castro wrote:
> > lvds-encoder.c implementation is also suitable for LVDS decoders,
> > not just LVDS encoders.
> > Instead of creating a new driver for addressing support for
> > transparent LVDS decoders, repurpose lvds-encoder.c for the greater
> > good.
> >
> > Signed-off-by: Fabrizio Castro <fabrizio.cas...@bp.renesas.com>
> >
> > ---
> > v2->v3:
> > * No change
> > v1->v2:
> > * No change
> > ---
> > drivers/gpu/drm/bridge/Kconfig | 8 +-
> > drivers/gpu/drm/bridge/Makefile | 2 +-
> > drivers/gpu/drm/bridge/lvds-codec.c | 131 ++++++++++++++++++++++++++++
> > drivers/gpu/drm/bridge/lvds-encoder.c | 155
> > ----------------------------------
> > 4 files changed, 136 insertions(+), 160 deletions(-)
>
> It would help if you added the -M1 option to git-format-patch to detect
> the rename, the result would be easier to review.
Will do, thank you for the hint
>
> > create mode 100644 drivers/gpu/drm/bridge/lvds-codec.c
> > delete mode 100644 drivers/gpu/drm/bridge/lvds-encoder.c
> >
> > diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
> > index 3436297..9e75ca4e 100644
> > --- a/drivers/gpu/drm/bridge/Kconfig
> > +++ b/drivers/gpu/drm/bridge/Kconfig
> > @@ -45,14 +45,14 @@ config DRM_DUMB_VGA_DAC
> > Support for non-programmable RGB to VGA DAC bridges, such as ADI
> > ADV7123, TI THS8134 and THS8135 or passive resistor ladder DACs.
> >
> > -config DRM_LVDS_ENCODER
> > - tristate "Transparent parallel to LVDS encoder support"
> > +config DRM_LVDS_CODEC
> > + tristate "Transparent LVDS encoders and decoders support"
> > depends on OF
> > select DRM_KMS_HELPER
> > select DRM_PANEL_BRIDGE
> > help
> > - Support for transparent parallel to LVDS encoders that don't require
> > - any configuration.
> > + Support for transparent LVDS encoders and LVDS decoders that don't
> > + require any configuration.
> >
> > config DRM_MEGACHIPS_STDPXXXX_GE_B850V3_FW
> > tristate "MegaChips stdp4028-ge-b850v3-fw and stdp2690-ge-b850v3-fw"
> > diff --git a/drivers/gpu/drm/bridge/Makefile
> > b/drivers/gpu/drm/bridge/Makefile
> > index 4934fcf..8a9178a 100644
> > --- a/drivers/gpu/drm/bridge/Makefile
> > +++ b/drivers/gpu/drm/bridge/Makefile
> > @@ -2,7 +2,7 @@
> > obj-$(CONFIG_DRM_ANALOGIX_ANX78XX) += analogix-anx78xx.o
> > obj-$(CONFIG_DRM_CDNS_DSI) += cdns-dsi.o
> > obj-$(CONFIG_DRM_DUMB_VGA_DAC) += dumb-vga-dac.o
> > -obj-$(CONFIG_DRM_LVDS_ENCODER) += lvds-encoder.o
> > +obj-$(CONFIG_DRM_LVDS_CODEC) += lvds-codec.o
> > obj-$(CONFIG_DRM_MEGACHIPS_STDPXXXX_GE_B850V3_FW) +=
> > megachips-stdpxxxx-ge-b850v3-fw.o
> > obj-$(CONFIG_DRM_NXP_PTN3460) += nxp-ptn3460.o
> > obj-$(CONFIG_DRM_PARADE_PS8622) += parade-ps8622.o
> > diff --git a/drivers/gpu/drm/bridge/lvds-codec.c
> > b/drivers/gpu/drm/bridge/lvds-codec.c
> > new file mode 100644
> > index 0000000..d57a8eb
> > --- /dev/null
> > +++ b/drivers/gpu/drm/bridge/lvds-codec.c
> > @@ -0,0 +1,131 @@
> > +// SPDX-License-Identifier: GPL-2.0-or-later
> > +/*
> > + * Copyright (C) 2019 Renesas Electronics Corporation
> > + * Copyright (C) 2016 Laurent Pinchart <laurent.pinch...@ideasonboard.com>
> > + */
> > +
> > +#include <linux/gpio/consumer.h>
> > +#include <linux/module.h>
> > +#include <linux/of.h>
> > +#include <linux/of_device.h>
> > +#include <linux/of_graph.h>
> > +#include <linux/platform_device.h>
> > +
> > +#include <drm/drm_bridge.h>
> > +#include <drm/drm_panel.h>
> > +
> > +struct lvds_codec {
> > + struct drm_bridge bridge;
> > + struct drm_bridge *panel_bridge;
> > + struct gpio_desc *powerdown_gpio;
> > +};
> > +
> > +static int lvds_codec_attach(struct drm_bridge *bridge)
> > +{
> > + struct lvds_codec *lvds_codec = container_of(bridge,
> > + struct lvds_codec, bridge);
> > +
> > + return drm_bridge_attach(bridge->encoder, lvds_codec->panel_bridge,
> > + bridge);
> > +}
> > +
> > +static void lvds_codec_enable(struct drm_bridge *bridge)
> > +{
> > + struct lvds_codec *lvds_codec = container_of(bridge,
> > + struct lvds_codec, bridge);
> > +
> > + if (lvds_codec->powerdown_gpio)
> > + gpiod_set_value_cansleep(lvds_codec->powerdown_gpio, 0);
> > +}
> > +
> > +static void lvds_codec_disable(struct drm_bridge *bridge)
> > +{
> > + struct lvds_codec *lvds_codec = container_of(bridge,
> > + struct lvds_codec, bridge);
> > +
> > + if (lvds_codec->powerdown_gpio)
> > + gpiod_set_value_cansleep(lvds_codec->powerdown_gpio, 1);
> > +}
> > +
> > +static struct drm_bridge_funcs funcs = {
> > + .attach = lvds_codec_attach,
> > + .enable = lvds_codec_enable,
> > + .disable = lvds_codec_disable,
> > +};
> > +
> > +static int lvds_codec_probe(struct platform_device *pdev)
> > +{
> > + struct device *dev = &pdev->dev;
> > + struct device_node *panel_node;
> > + struct drm_panel *panel;
> > + struct lvds_codec *lvds_codec;
> > +
> > + lvds_codec = devm_kzalloc(dev, sizeof(*lvds_codec), GFP_KERNEL);
> > + if (!lvds_codec)
> > + return -ENOMEM;
> > +
> > + lvds_codec->powerdown_gpio = devm_gpiod_get_optional(dev, "powerdown",
> > + GPIOD_OUT_HIGH);
> > + if (IS_ERR(lvds_codec->powerdown_gpio))
> > + return PTR_ERR(lvds_codec->powerdown_gpio);
>
> The driver had an error message here, any reason it got removed ?
I am quoting from https://www.spinics.net/lists/devicetree/msg318602.html :
"I know it was there already, but this seems a bit unusual for the
minimal gain of having a printout in the very unlikely case the
gpiod_get() operations fails. I would just return PTR_ERR()."
I am OK with reinstating it, just let me know what you want me to do here.
>
> > +
> > + panel_node = of_graph_get_remote_node(dev->of_node, 1, 0);
> > + if (!panel_node) {
> > + dev_dbg(dev, "panel DT node not found\n");
> > + return -ENXIO;
> > + }
> > +
> > + panel = of_drm_find_panel(panel_node);
> > + of_node_put(panel_node);
> > + if (IS_ERR(panel)) {
> > + dev_dbg(dev, "panel not found, deferring probe\n");
> > + return PTR_ERR(panel);
> > + }
> > +
> > + lvds_codec->panel_bridge = devm_drm_panel_bridge_add(dev, panel);
>
> This was devm_drm_panel_bridge_add_typed(), do you think there's a risk
> of breaking userspace ? Of course as noted in the documentation of
> devm_drm_panel_bridge_add_typed() the right solution is to fix panel
> drivers, but I'm still slightly worried.
Things break when the panel doesn't define connector_type, leading to the below
check from devm_drm_panel_bridge_add:
if (WARN_ON(panel->connector_type == DRM_MODE_CONNECTOR_Unknown))
return NULL;
Please advise on the best course of action here.
>
> Actually, could you split this patch in two, with a patch that only
> renames the driver (and the symbols internally) without any functional
> change, and another patch that performs the modifications ? That would
> be much easier to review and discuss.
Will do
>
> > + if (IS_ERR(lvds_codec->panel_bridge))
> > + return PTR_ERR(lvds_codec->panel_bridge);
> > +
> > + /* The panel_bridge bridge is attached to the panel's of_node,
> > + * but we need a bridge attached to our of_node for our user
> > + * to look up.
> > + */
> > + lvds_codec->bridge.of_node = dev->of_node;
> > + lvds_codec->bridge.funcs = &funcs;
> > + drm_bridge_add(&lvds_codec->bridge);
> > +
> > + platform_set_drvdata(pdev, lvds_codec);
> > +
> > + return 0;
> > +}
> > +
> > +static int lvds_codec_remove(struct platform_device *pdev)
> > +{
> > + struct lvds_codec *lvds_codec = platform_get_drvdata(pdev);
> > +
> > + drm_bridge_remove(&lvds_codec->bridge);
> > +
> > + return 0;
> > +}
> > +
> > +static const struct of_device_id lvds_codec_match[] = {
> > + { .compatible = "lvds-encoder" },
> > + { .compatible = "thine,thc63lvdm83d" },
> > + { .compatible = "lvds-decoder" },
> > + {},
> > +};
> > +MODULE_DEVICE_TABLE(of, lvds_codec_match);
> > +
> > +static struct platform_driver lvds_codec_driver = {
> > + .probe = lvds_codec_probe,
> > + .remove = lvds_codec_remove,
> > + .driver = {
> > + .name = "lvds-codec",
> > + .of_match_table = lvds_codec_match,
> > + },
> > +};
> > +module_platform_driver(lvds_codec_driver);
> > +
> > +MODULE_AUTHOR("Laurent Pinchart <laurent.pinch...@ideasonboard.com>");
> > +MODULE_DESCRIPTION("Driver for transparent LVDS encoders and LVDS
> > decoders");
>
> Maybe "LVDS encoders and decoders" ?
>
> > +MODULE_LICENSE("GPL");
>
> [snip]
>
> --
> Regards,
>
> Laurent Pinchart
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