Re: [PATCH v6 09/18] drm/bridge: inno-hdmi: Allow the register map to come from a parent

[Heiko Stuebner <heiko@sntech.de>]

Am Donnerstag, 29. Oktober 2026, 08:53:43 Mitteleuropäische Normalzeit schrieb Michal Wilczynski:
> On some SoCs the HDMI controller does not own its register window. The
> StarFive JH7110 documents one 64 KB block, u0_hdmitx, that holds both
> the controller and the PHY, so the parent device maps it and owns the
> regmap while the two children share it.
> 
> Use a regmap supplied by the parent device when there is one, and keep
> mapping our own resource when there is not, so platforms that own their
> register window are unaffected.
> 
> Reviewed-by: Joshua Peisach <jpeisach@ubuntu.com>
> Tested-by: Byron Stanoszek <gandalf@winds.org>
> Tested-by: OOHehir <oo.hehir@gmail.com>
> Signed-off-by: Michal Wilczynski <m.wilczynski@samsung.com>
> ---
>  drivers/gpu/drm/bridge/inno-hdmi.c | 31 ++++++++++++++++++++++++++++---
>  1 file changed, 28 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/inno-hdmi.c b/drivers/gpu/drm/bridge/inno-hdmi.c
> index 222f6522844ee60ae9a07ab2dcca748dbf7403e4..a8905bf627a224d7e3918514195f1810164dc26f 100644
> --- a/drivers/gpu/drm/bridge/inno-hdmi.c
> +++ b/drivers/gpu/drm/bridge/inno-hdmi.c
> @@ -397,6 +397,7 @@ struct inno_hdmi {
>  	struct clk *pclk;
>  	struct clk *refclk;
>  	void __iomem *regs;
> +	struct regmap *regmap;
>  	struct regmap *grf;
>  
>  	struct inno_hdmi_i2c *i2c;
> @@ -470,11 +471,25 @@ static int inno_hdmi_find_phy_config(struct inno_hdmi *hdmi,
>  
>  static inline u8 hdmi_readb(struct inno_hdmi *hdmi, u16 offset)
>  {
> +	u32 val;
> +
> +	if (hdmi->regmap) {
> +		if (regmap_read(hdmi->regmap, offset * 4, &val))
> +			return 0;
> +
> +		return val;
> +	}
> +
>  	return readl_relaxed(hdmi->regs + (offset) * 0x04);
>  }
>  
>  static inline void hdmi_writeb(struct inno_hdmi *hdmi, u16 offset, u32 val)
>  {
> +	if (hdmi->regmap) {
> +		regmap_write(hdmi->regmap, offset * 4, val);
> +		return;
> +	}
> +
>  	writel_relaxed(val, hdmi->regs + (offset) * 0x04);
>  }
>  
> @@ -1101,9 +1116,19 @@ struct inno_hdmi *inno_hdmi_probe(struct platform_device *pdev,
>  	hdmi->dev = dev;
>  	hdmi->plat_data = plat_data;
>  
> -	hdmi->regs = devm_platform_ioremap_resource(pdev, 0);
> -	if (IS_ERR(hdmi->regs))
> -		return ERR_CAST(hdmi->regs);
> +	/*
> +	 * On platforms where the controller shares a register space with
> +	 * other blocks, the parent owns the regmap. Fall back to mapping
> +	 * our own resource where it does not.
> +	 */
> +	if (dev->parent)
> +		hdmi->regmap = dev_get_regmap(dev->parent, NULL);
> +
> +	if (!hdmi->regmap) {
> +		hdmi->regs = devm_platform_ioremap_resource(pdev, 0);
> +		if (IS_ERR(hdmi->regs))
> +			return ERR_CAST(hdmi->regs);
> +	}

why can't you just also use a mmio regmap here? Because with this change
the driver now has 2 competing register interfaces and you need those
conditionals all the time.

Just convert the existing user to also use a regmap please.


Heiko