Re: [PATCH v5 21/34] drm/mediatek: mtk_hdmi: Move CEC device parsing in new function

[AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>]

Il 07/02/25 15:45, Alexandre Mergnat ha scritto:
> On 13/01/2025 15:52, AngeloGioacchino Del Regno wrote:
> > Move the CEC device parsing logic to a new function called
> > mtk_hdmi_get_cec_dev(), and move the parsing action to the end
> > of mtk_hdmi_dt_parse_pdata(), allowing to remove gotos in this
> > function, reducing code size and improving readability.
>
> Why CEC device parsing logic isn't done mtk_cec.c driver ? Then add 
> "mtk_cec_get_dev" function to mtk_cec.c too. Finally, call this new function in 
> mtk_hdmi_probe after mtk_hdmi_dt_parse_pdata().
>
> > Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>
> > ---
> >   drivers/gpu/drm/mediatek/mtk_hdmi.c | 84 ++++++++++++++---------------
> >   1 file changed, 40 insertions(+), 44 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/mediatek/mtk_hdmi.c b/drivers/gpu/drm/mediatek/ 
> > mtk_hdmi.c
> > index 48c37294dcbb..eb285ec394a3 100644
> > --- a/drivers/gpu/drm/mediatek/mtk_hdmi.c
> > +++ b/drivers/gpu/drm/mediatek/mtk_hdmi.c
> > @@ -1367,24 +1367,16 @@ static const struct drm_bridge_funcs 
> > mtk_hdmi_bridge_funcs = {
> >       .edid_read = mtk_hdmi_bridge_edid_read,
> >   };
> > -static int mtk_hdmi_dt_parse_pdata(struct mtk_hdmi *hdmi,
> > -                   struct platform_device *pdev)
> > +static int mtk_hdmi_get_cec_dev(struct mtk_hdmi *hdmi, struct device *dev, 
> > struct device_node *np)
> >   {
> > -    struct device *dev = &pdev->dev;
> > -    struct device_node *np = dev->of_node;
> > -    struct device_node *remote, *i2c_np;
> >       struct platform_device *cec_pdev;
> > -    struct regmap *regmap;
> > +    struct device_node *cec_np;
> >       int ret;
> > -    ret = mtk_hdmi_get_all_clk(hdmi, np);
> > -    if (ret)
> > -        return dev_err_probe(dev, ret, "Failed to get clocks\n");
> > -
> >       /* The CEC module handles HDMI hotplug detection */
> >       cec_np = of_get_compatible_child(np->parent, "mediatek,mt8173-cec");
>
> If it's done in mtk_cec.c, the hardcoded compatible string method will be replaced 
> by of_match_table (mtk_cec_of_ids), which is scalable and consistent.

That's true, yes, but the CEC driver is not supposed to be in drivers/drm/mediatek
in the first place - that should be partially refactored and moved to where the CEC
drivers belong: drivers/media/cec/platform/mediatek/

This is something that is currently in the process of making here, as the CEC v2
driver will be added there, and the CECv1 driver will be moved along side of the
new one, making things finally correct.

Of course, this code will be retained to keep retrocompatibility with older device
trees, and if I move it to mtk_cec, I will have to move it back here after the
CEC driver is moved to the correct location.

For the reasons explained above, I disagree about moving this code to the CEC
driver.

Cheers,
Angelo

> >       if (!cec_np)
> > -        return dev_err_probe(dev, -EINVAL, "Failed to find CEC node\n");
> > +        return dev_err_probe(dev, -ENOTSUPP, "Failed to find CEC node\n");
> >       cec_pdev = of_find_device_by_node(cec_np);
> >       if (!cec_pdev) {
> > @@ -1393,65 +1385,69 @@ static int mtk_hdmi_dt_parse_pdata(struct mtk_hdmi *hdmi,
> >           return -EPROBE_DEFER;
> >       }
> >       of_node_put(cec_np);
> > -    hdmi->cec_dev = &cec_pdev->dev;
> >       /*
> >        * The mediatek,syscon-hdmi property contains a phandle link to the
> >        * MMSYS_CONFIG device and the register offset of the HDMI_SYS_CFG
> >        * registers it contains.
> >        */
> > -    regmap = syscon_regmap_lookup_by_phandle(np, "mediatek,syscon-hdmi");
> > -    ret = of_property_read_u32_index(np, "mediatek,syscon-hdmi", 1,
> > -                     &hdmi->sys_offset);
> > -    if (IS_ERR(regmap))
> > -        ret = PTR_ERR(regmap);
> > -    if (ret) {
> > -        dev_err_probe(dev, ret,
> > -                  "Failed to get system configuration registers\n");
> > -        goto put_device;
> > -    }
> > -    hdmi->sys_regmap = regmap;
> > +    hdmi->sys_regmap = syscon_regmap_lookup_by_phandle(np, "mediatek,syscon-hdmi");
> > +    if (IS_ERR(hdmi->sys_regmap))
> > +        return PTR_ERR(hdmi->sys_regmap);
> > +
> > +    ret = of_property_read_u32_index(np, "mediatek,syscon-hdmi", 1, &hdmi- 
> > >sys_offset);
> > +    if (ret)
> > +        return dev_err_probe(dev, ret,
> > +                     "Failed to get system configuration registers\n");
> > +
> > +    hdmi->cec_dev = &cec_pdev->dev;
> > +    return 0;
> > +}
> > +
> > +static int mtk_hdmi_dt_parse_pdata(struct mtk_hdmi *hdmi,
> > +                   struct platform_device *pdev)
> > +{
> > +    struct device *dev = &pdev->dev;
> > +    struct device_node *np = dev->of_node;
> > +    struct device_node *remote, *i2c_np;
> > +    int ret;
> > +
> > +    ret = mtk_hdmi_get_all_clk(hdmi, np);
> > +    if (ret)
> > +        return dev_err_probe(dev, ret, "Failed to get clocks\n");
> >       hdmi->regs = device_node_to_regmap(dev->of_node);
> > -    if (IS_ERR(hdmi->regs)) {
> > -        ret = PTR_ERR(hdmi->regs);
> > -        goto put_device;
> > -    }
> > +    if (IS_ERR(hdmi->regs))
> > +        return PTR_ERR(hdmi->regs);
> >       remote = of_graph_get_remote_node(np, 1, 0);
> > -    if (!remote) {
> > -        ret = -EINVAL;
> > -        goto put_device;
> > -    }
> > +    if (!remote)
> > +        return -EINVAL;
> >       if (!of_device_is_compatible(remote, "hdmi-connector")) {
> >           hdmi->next_bridge = of_drm_find_bridge(remote);
> >           if (!hdmi->next_bridge) {
> >               dev_err(dev, "Waiting for external bridge\n");
> >               of_node_put(remote);
> > -            ret = -EPROBE_DEFER;
> > -            goto put_device;
> > +            return -EPROBE_DEFER;
> >           }
> >       }
> >       i2c_np = of_parse_phandle(remote, "ddc-i2c-bus", 0);
> >       of_node_put(remote);
> > -    if (!i2c_np) {
> > -        ret = dev_err_probe(dev, -EINVAL, "No ddc-i2c-bus in connector\n");
> > -        goto put_device;
> > -    }
> > +    if (!i2c_np)
> > +        return dev_err_probe(dev, -EINVAL, "No ddc-i2c-bus in connector\n");
> >       hdmi->ddc_adpt = of_find_i2c_adapter_by_node(i2c_np);
> >       of_node_put(i2c_np);
> > -    if (!hdmi->ddc_adpt) {
> > -        ret = dev_err_probe(dev, -EINVAL, "Failed to get ddc i2c adapter by 
> > node\n");
> > -        goto put_device;
> > -    }
> > +    if (!hdmi->ddc_adpt)
> > +        return dev_err_probe(dev, -EINVAL, "Failed to get ddc i2c adapter by 
> > node\n");
> > +
> > +    ret = mtk_hdmi_get_cec_dev(hdmi, dev, np);
> > +    if (ret)
> > +        return ret;
> >       return 0;
> > -put_device:
> > -    put_device(hdmi->cec_dev);
> > -    return ret;
> >   }
> >   /*