Re: [PATCH 2/2] drm/panel: add BOE tv101wum-ll2 panel driver

[Neil Armstrong <neil.armstrong@linaro.org>]

On 23/07/2024 21:17, Doug Anderson wrote:
> Hi,
> 
> On Tue, Jul 9, 2024 at 6:06 AM Neil Armstrong <neil.armstrong@linaro.org> wrote:
>>
>> diff --git a/drivers/gpu/drm/panel/Makefile b/drivers/gpu/drm/panel/Makefile
>> index 5581387707c6..79c90894b6a4 100644
>> --- a/drivers/gpu/drm/panel/Makefile
>> +++ b/drivers/gpu/drm/panel/Makefile
>> @@ -7,6 +7,7 @@ obj-$(CONFIG_DRM_PANEL_BOE_BF060Y8M_AJ0) += panel-boe-bf060y8m-aj0.o
>>   obj-$(CONFIG_DRM_PANEL_BOE_HIMAX8279D) += panel-boe-himax8279d.o
>>   obj-$(CONFIG_DRM_PANEL_BOE_TH101MB31UIG002_28A) += panel-boe-th101mb31ig002-28a.o
>>   obj-$(CONFIG_DRM_PANEL_BOE_TV101WUM_NL6) += panel-boe-tv101wum-nl6.o
>> +obj-$(CONFIG_DRM_PANEL_BOE_TV101WUM_LL2) += panel-boe-tv101wum-ll2.o
> 
> nit: please sort. L comes before N.

Good catch, thx

> 
> 
>>   obj-$(CONFIG_DRM_PANEL_DSI_CM) += panel-dsi-cm.o
>>   obj-$(CONFIG_DRM_PANEL_LVDS) += panel-lvds.o
>>   obj-$(CONFIG_DRM_PANEL_SIMPLE) += panel-simple.o
>> diff --git a/drivers/gpu/drm/panel/panel-boe-tv101wum-ll2.c b/drivers/gpu/drm/panel/panel-boe-tv101wum-ll2.c
>> new file mode 100644
>> index 000000000000..5513cb48d949
>> --- /dev/null
>> +++ b/drivers/gpu/drm/panel/panel-boe-tv101wum-ll2.c
>> @@ -0,0 +1,240 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +// Generated with linux-mdss-dsi-panel-driver-generator from vendor device tree:
>> +//   Copyright (c) 2013, The Linux Foundation. All rights reserved.
>> +//   Copyright (c) 2024, Neil Armstrong <neil.armstrong@linaro.org>
>> +
>> +#include <linux/delay.h>
>> +#include <linux/gpio/consumer.h>
>> +#include <linux/regulator/consumer.h>
>> +#include <linux/module.h>
>> +#include <linux/of.h>
> 
> nit: sort header files?

Will do while I'm it, but I don't personally care of the include order..

> 
>> +static int boe_tv101wum_ll2_prepare(struct drm_panel *panel)
>> +{
>> +       struct boe_tv101wum_ll2 *ctx = to_boe_tv101wum_ll2(panel);
>> +       struct device *dev = &ctx->dsi->dev;
>> +       int ret;
>> +
>> +       ret = regulator_bulk_enable(ARRAY_SIZE(ctx->supplies),
>> +                                   ctx->supplies);
>> +       if (ret < 0)
>> +               return ret;
>> +
>> +       boe_tv101wum_ll2_reset(ctx);
>> +
>> +       ret = boe_tv101wum_ll2_on(ctx);
>> +       if (ret < 0) {
>> +               dev_err(dev, "Failed to initialize panel: %d\n", ret);
> 
> nit: Do you really need this error message? The "_multi" variants are
> all chatty and print the error message, so we don't really need this
> here...

Yeah you're right, it's a leftover of the linux-mdss-dsi-panel-driver-generator

> 
> 
>> +               gpiod_set_value_cansleep(ctx->reset_gpio, 1);
>> +               return ret;
> 
> Shouldn't you turn off the regulators?

Indeed

> 
> 
>> +static int boe_tv101wum_ll2_unprepare(struct drm_panel *panel)
>> +{
>> +       struct boe_tv101wum_ll2 *ctx = to_boe_tv101wum_ll2(panel);
>> +       struct device *dev = &ctx->dsi->dev;
>> +       int ret;
>> +
>> +       ret = boe_tv101wum_ll2_off(ctx);
>> +       if (ret < 0)
>> +               dev_err(dev, "Failed to un-initialize panel: %d\n", ret);
> 
> nit: Do you really need this error message? The "_multi" variants are
> all chatty and print the error message, so we don't really need this
> here...

Another leftover

> 
> 
>> +
>> +       gpiod_set_value_cansleep(ctx->reset_gpio, 1);
>> +
>> +       regulator_bulk_disable(ARRAY_SIZE(ctx->supplies), ctx->supplies);
>> +
>> +       return 0;
> 
> Maybe add a comment justifying why you don't return the error code
> that boe_tv101wum_ll2_off() returned?

Good point, as far as I remember I always avoided returning errors
when disabling things, I'll investigate

> 
> 
>> +static int boe_tv101wum_ll2_get_modes(struct drm_panel *panel,
>> +                                     struct drm_connector *connector)
>> +{
>> +       return drm_connector_helper_get_modes_fixed(connector, &boe_tv101wum_ll2_mode);
> 
> Random question for you: on panels that don't use the
> drm_connector_helper the "bpc" gets set here. Is there a reason why
> some panel drivers (like this one) don't set bpc?

Good question, I'll check

> 
> 
>> +static int boe_tv101wum_ll2_probe(struct mipi_dsi_device *dsi)
>> +{
>> +       struct device *dev = &dsi->dev;
>> +       struct boe_tv101wum_ll2 *ctx;
>> +       int ret;
>> +
>> +       ctx = devm_kzalloc(dev, sizeof(*ctx), GFP_KERNEL);
>> +       if (!ctx)
>> +               return -ENOMEM;
>> +
>> +       ctx->supplies[0].supply = "vsp";
>> +       ctx->supplies[1].supply = "vsn";
>> +
>> +       ret = devm_regulator_bulk_get(&dsi->dev, ARRAY_SIZE(ctx->supplies),
>> +                                     ctx->supplies);
> 
> Any chance I can convince you to use devm_regulator_bulk_get_const()?
> Then you can list your supply structures as "static const" instead of
> having to initialize them via code.

You convinced me!

> 
> 
>> +       if (ret < 0)
>> +               return ret;
>> +
>> +       ctx->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);
>> +       if (IS_ERR(ctx->reset_gpio))
>> +               return dev_err_probe(dev, PTR_ERR(ctx->reset_gpio),
>> +                                    "Failed to get reset-gpios\n");
>> +
>> +       ctx->dsi = dsi;
>> +       mipi_dsi_set_drvdata(dsi, ctx);
>> +
>> +       dsi->lanes = 4;
>> +       dsi->format = MIPI_DSI_FMT_RGB888;
>> +       dsi->mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_BURST |
>> +                         MIPI_DSI_MODE_VIDEO_HSE;
>> +
>> +       drm_panel_init(&ctx->panel, dev, &boe_tv101wum_ll2_panel_funcs,
>> +                      DRM_MODE_CONNECTOR_DSI);
>> +       ctx->panel.prepare_prev_first = true;
>> +
>> +       ret = drm_panel_of_backlight(&ctx->panel);
>> +       if (ret)
>> +               return dev_err_probe(dev, ret, "Failed to get backlight\n");
>> +
>> +       drm_panel_add(&ctx->panel);
> 
> Any chance you could add devm_drm_panel_add() and then use it? Then
> you can fully get rid of your remove and error handling since
> devm_mipi_dsi_attach() already exists. Note that this would not change
> object lifetimes at all since you're already calling
> drm_panel_remove() in your remove code--it would just clean up the
> code...

Yep I'll use it

> 
> 
>> +static struct mipi_dsi_driver boe_tv101wum_ll2_driver = {
>> +       .probe = boe_tv101wum_ll2_probe,
>> +       .remove = boe_tv101wum_ll2_remove,
>> +       .driver = {
>> +               .name = "panel-boe-tv101wum_ll2",
>> +               .of_match_table = boe_tv101wum_ll2_of_match,
>> +       },
>> +};
>> +module_mipi_dsi_driver(boe_tv101wum_ll2_driver);
>> +
>> +MODULE_DESCRIPTION("DRM driver for Boe TV101WUM-LL2 Panel");
> 
> Should "Boe" be "BOE" ?

Good point aswell!

Thanks for the review

Neil