Re: [PATCH 6/6] drm/meson: add support for MIPI-DSI transceiver

[Martin Blumenstingl]

Hi Neil,

some high-level comments from me below.

On Fri, Jan 7, 2022 at 3:58 PM Neil Armstrong <narmstrong@xxxxxxxxxxxx> 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.

[...]
> +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?

[...]
> +       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

[...]
> +       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

[...]
> +       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");


Best regards,
Martin