linux-kernel - Re: [PATCH v4 02/10] media: platform: Add c3 mipi csi2 driver

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Message-ID: <5sen6lv5xg4hjdc4j2l6k5iywqpllbutoaebyln74aeuplawtu@nmpmzgwkkgih>
Date: Thu, 12 Dec 2024 09:41:16 +0100
From: Jacopo Mondi <jacopo.mondi@...asonboard.com>
To: keke.li@...ogic.com, 
	Laurent Pinchart <laurent.pinchart@...asonboard.com>, Sakari Ailus <sakari.ailus@...ux.intel.com>
Cc: Mauro Carvalho Chehab <mchehab@...nel.org>, 
	Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, 
	Conor Dooley <conor+dt@...nel.org>, linux-media@...r.kernel.org, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org, kieran.bingham@...asonboard.com, 
	laurent.pinchart@...asonboard.com, dan.scally@...asonboard.com
Subject: Re: [PATCH v4 02/10] media: platform: Add c3 mipi csi2 driver

Hi Keke,
  a question for Laurent and Sakari

On Thu, Dec 05, 2024 at 05:04:28PM +0800, Keke Li via B4 Relay wrote:
> From: Keke Li <keke.li@...ogic.com>
>
> This driver is used to receive mipi data from image sensor.
>
> Reviewed-by: Daniel Scally <dan.scally@...asonboard.com>
> Signed-off-by: Keke Li <keke.li@...ogic.com>

[snip]

> +
> +static int c3_mipi_csi_configure_clocks(struct csi_device *csi)
> +{
> +	const struct csi_info *info = csi->info;
> +	int ret;
> +	u32 i;
> +
> +	for (i = 0; i < info->clock_num; i++)
> +		csi->clks[i].id = info->clocks[i];
> +
> +	ret = devm_clk_bulk_get(csi->dev, info->clock_num, csi->clks);
> +	if (ret)
> +		return ret;
> +
> +	for (i = 0; i < info->clock_num; i++) {
> +		if (!info->clock_rates[i])
> +			continue;
> +		ret = clk_set_rate(csi->clks[i].clk, info->clock_rates[i]);
> +		if (ret) {
> +			dev_err(csi->dev, "Failed to set %s rate %u\n", info->clocks[i],
> +				info->clock_rates[i]);
> +			return ret;
> +		}
> +	}
> +
> +	return 0;
> +}
> +

[snip]

> +
> +static const struct csi_info c3_mipi_csi_info = {
> +	.clocks = {"vapb", "phy0"},
> +	.clock_rates = {0, 200000000},
> +	.clock_num = 2
> +};
> +
> +static const struct of_device_id c3_mipi_csi_of_match[] = {
> +	{ .compatible = "amlogic,c3-mipi-csi2",
> +	  .data = &c3_mipi_csi_info,
> +	},
> +	{ },
> +};

All the drivers in this patch series implement the same pattern when
it comes to handling clock. There's a list of clock providers in the
driver associated with a clock frequency. The driver bulk_get the
clocks and set_rate() using the per-compatible info table.

Do you think this should rather come from dts using the
assigned-clocks and assigned-clock-rates properties ?