Subject: Re: [PATCH 6/6] drm/meson: add support for MIPI-DSI transceiver
To:     Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Cc:     dri-devel@lists.freedesktop.org, linux-amlogic@lists.infradead.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
References: <20220107145515.613009-1-narmstrong@baylibre.com>
 <20220107145515.613009-7-narmstrong@baylibre.com>
 <CAFBinCB3+dSjQFRp5CBpGk5Qi8zoxRDRaobuCtXzU6VtM8+ryQ@mail.gmail.com>
From:   Neil Armstrong <narmstrong@baylibre.com>
Organization: Baylibre
Message-ID: <508ea2d7-aee3-9409-023c-638b09d733b0@baylibre.com>
Date:   Mon, 10 Jan 2022 10:51:49 +0100
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On 07/01/2022 23:49, Martin Blumenstingl wrote:
> Hi Neil,
> 
> some high-level comments from me below.
> 
> On Fri, Jan 7, 2022 at 3:58 PM Neil Armstrong <narmstrong@baylibre.com> wrote:
> [...]
>> +/*  MIPI DSI Relative REGISTERs Definitions */
>> +/* For MIPI_DSI_TOP_CNTL */
>> +#define BIT_DPI_COLOR_MODE        20
>> +#define BIT_IN_COLOR_MODE         16
>> +#define BIT_CHROMA_SUBSAMPLE      14
>> +#define BIT_COMP2_SEL             12
>> +#define BIT_COMP1_SEL             10
>> +#define BIT_COMP0_SEL              8
>> +#define BIT_DE_POL                 6
>> +#define BIT_HSYNC_POL              5
>> +#define BIT_VSYNC_POL              4
>> +#define BIT_DPICOLORM              3
>> +#define BIT_DPISHUTDN              2
>> +#define BIT_EDPITE_INTR_PULSE      1
>> +#define BIT_ERR_INTR_PULSE         0
> Why not use BIT() and GENMASK() for these and prefixing them with
> MIPI_DSI_TOP_CNTL_?
> That would make them consistent with other parts of the meson sub-driver.

Yeah it was a lousy copy-paste from vendor driver, and I was lazy, but I'll fix this.

> 
> [...]
>> +static void meson_dw_mipi_dsi_hw_init(struct meson_dw_mipi_dsi *mipi_dsi)
>> +{
>> +       writel_relaxed((1 << 4) | (1 << 5) | (0 << 6),
>> +                      mipi_dsi->base + MIPI_DSI_TOP_CNTL);
> please use the macros from above
> 
>> +       writel_bits_relaxed(0xf, 0xf, mipi_dsi->base + MIPI_DSI_TOP_SW_RESET);
>> +       writel_bits_relaxed(0xf, 0, mipi_dsi->base + MIPI_DSI_TOP_SW_RESET);
> 
> [...]
>> +       phy_power_on(mipi_dsi->phy);
> Please propagate the error code here.
> Also shouldn't this go to a new dw_mipi_dsi_phy_power_on() as the PHY
> driver uses the updated settings from phy_configure only in it's
> .power_on callback?

Good point, let me check that.

> 
> [...]
>> +       phy_configure(mipi_dsi->phy, &mipi_dsi->phy_opts);
> please propagate the error code here as the PHY driver has some
> explicit code to return an error in it's .phy_configure callback
> 
> [...]
>> +       phy_init(mipi_dsi->phy);
> please propagate the error code here
> 
> [...]
>> +       phy_exit(mipi_dsi->phy);
> please propagate the error code here

ok for the 3

> 
> [...]
>> +       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +       mipi_dsi->base = devm_ioremap_resource(&pdev->dev, res);
> other parts of the meson DRM driver have been converted to use
> devm_platform_ioremap_resource()
> I suggest updating this as well to simplify the code here

Yep, again lazyness

> 
> [...]
>> +       mipi_dsi->phy = devm_phy_get(&pdev->dev, "dphy");
>> +       if (IS_ERR(mipi_dsi->phy)) {
>> +               ret = PTR_ERR(mipi_dsi->phy);
>> +               dev_err(&pdev->dev, "failed to get mipi dphy: %d\n", ret);
>> +               return ret;
> you can simplify this with:
>   return dev_err_probe(&pdev->dev, PTR_ERR(mipi_dsi->phy, "failed to
> get mipi dphy\n");
> 
> [...]
>> +       mipi_dsi->px_clk = devm_clk_get(&pdev->dev, "px_clk");
>> +       if (IS_ERR(mipi_dsi->px_clk)) {
>> +               dev_err(&pdev->dev, "Unable to get PLL clk\n");
>> +               return PTR_ERR(mipi_dsi->px_clk);
> you can simplify this with:
>   return dev_err_probe(&pdev->dev, PTR_ERR(mipi_dsi->px_clk, "Unable
> to get PLL clk\n");
> Also should it say s/PLL clk/px clock/?
> 
> [...]
>> +       top_rst = devm_reset_control_get_exclusive(&pdev->dev, "top");
>> +       if (IS_ERR(top_rst)) {
>> +               ret = PTR_ERR(top_rst);
>> +
>> +               if (ret != -EPROBE_DEFER)
>> +                       dev_err(&pdev->dev, "Unable to get reset control: %d\n", ret);
>> +
>> +               return ret;
> you can simplify this with:
>   return dev_err_probe(&pdev->dev, PTR_ERR(top_rst, "Unable to get
> reset control\n");
> 
> [...]
>> +       mipi_dsi->dmd = dw_mipi_dsi_probe(pdev, &mipi_dsi->pdata);
>> +       if (IS_ERR(mipi_dsi->dmd)) {
>> +               ret = PTR_ERR(mipi_dsi->dmd);
>> +               if (ret != -EPROBE_DEFER)
>> +                       dev_err(&pdev->dev,
>> +                               "Failed to probe dw_mipi_dsi: %d\n", ret);
> you can simplify this with:
>   dev_err_probe(&pdev->dev, ret, "Failed to probe dw_mipi_dsi\n");
>

Again 4 lazyness effects, will fix !

Thanks,
Neil


> 
> Best regards,
> Martin
>