Re: [RFC v2 2/5] drm/dsi: Try to match non-DT dsi devices

[Andrzej Hajda <a.hajda@samsung.com>]

On 10/06/2015 11:24 AM, Archit Taneja wrote:
> Add a device name field in mipi_dsi_device. This name is different from
> the actual dev name (which is of the format "hostname.reg"). When the
> device is created via DT, this name is set to the modalias string.
> In the non-DT case, the driver creating the DSI device provides the
> name by populating a filed in mipi_dsi_device_info.
>
> Matching for DT case would be as it was before. For the non-DT case,
> we compare the device and driver names. Matching by comparing driver and
> device names isn't the best thing to do. I'd appreciate some suggestions
> here.
>
> Other buses (like i2c/spi) perform a non-DT match by comparing the
> device name and entries in the driver's id_table. The id_table structs
> for different buses are defined in "include/linux/mod_devicetable.h", I
> didn't want to touch that for now.
>
> Signed-off-by: Archit Taneja <architt@codeaurora.org>
Beside small comments below.

Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>

> ---
>  drivers/gpu/drm/drm_mipi_dsi.c | 29 ++++++++++++++++++++++++++++-
>  include/drm/drm_mipi_dsi.h     |  8 ++++++++
>  2 files changed, 36 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/drm_mipi_dsi.c b/drivers/gpu/drm/drm_mipi_dsi.c
> index 245ecfe..46ee515 100644
> --- a/drivers/gpu/drm/drm_mipi_dsi.c
> +++ b/drivers/gpu/drm/drm_mipi_dsi.c
> @@ -45,9 +45,30 @@
>   * subset of the MIPI DCS command set.
>   */
>  
> +static const struct device_type mipi_dsi_device_type;
> +
>  static int mipi_dsi_device_match(struct device *dev, struct device_driver *drv)
>  {
> -	return of_driver_match_device(dev, drv);
> +	struct mipi_dsi_device *dsi;
> +
> +	if (dev->type == &mipi_dsi_device_type)
> +		dsi = to_mipi_dsi_device(dev);
> +	else
> +		return 0;
> +
> +	/* Attempt OF style match */
> +	if (of_driver_match_device(dev, drv))
> +		return 1;
> +
> +	/*
> +	 * Try to compare dsi device and driver names. If this matching approach
> +	 * isn't strong, we'd probably want the dsi drivers to populate the
> +	 * id_table field and use that instead
> +	 */
> +	if (!strcmp(dsi->name, drv->name))
> +		return 1;
> +
> +	return 0;
>  }
>  
>  static const struct dev_pm_ops mipi_dsi_device_pm_ops = {
> @@ -125,6 +146,7 @@ struct mipi_dsi_device *mipi_dsi_device_new(struct mipi_dsi_host *host,
>  	dsi->dev.type = &mipi_dsi_device_type;
>  	dsi->dev.of_node = info->node;
>  	dsi->channel = info->reg;
> +	strlcpy(dsi->name, info->name, sizeof(dsi->name));
>  
>  	dev_set_name(&dsi->dev, "%s.%d", dev_name(host->dev), info->reg);
>  
> @@ -147,6 +169,11 @@ of_mipi_dsi_device_add(struct mipi_dsi_host *host, struct device_node *node)
>  	int ret;
>  	u32 reg;
>  
> +	if (of_modalias_node(node, info.name, sizeof(info.name)) < 0) {
> +		dev_err(dev, "modalias failure on %s\n", node->full_name);
> +		return ERR_PTR(-EINVAL);
> +	}
> +
>  	ret = of_property_read_u32(node, "reg", &reg);
>  	if (ret) {
>  		dev_err(dev, "device node %s has no valid reg property: %d\n",
> diff --git a/include/drm/drm_mipi_dsi.h b/include/drm/drm_mipi_dsi.h
> index 90f4f3c..93dec7b 100644
> --- a/include/drm/drm_mipi_dsi.h
> +++ b/include/drm/drm_mipi_dsi.h
> @@ -139,8 +139,11 @@ enum mipi_dsi_pixel_format {
>  	MIPI_DSI_FMT_RGB565,
>  };
>  
> +#define DSI_DEV_NAME_SIZE		20
> +
>  /**
>   * struct mipi_dsi_device_info - template for creating a mipi_dsi_device
> + * @name: name of the dsi peripheral
>   * @reg: DSI virtual channel assigned to peripheral
>   * @node: pointer to OF device node
>   *
> @@ -148,14 +151,17 @@ enum mipi_dsi_pixel_format {
>   * DSI device
>   */
>  struct mipi_dsi_device_info {
> +	char name[DSI_DEV_NAME_SIZE];
I wonder if it shouldn't be called type as in case of i2c,
but no strong feelings.
>  	u32 reg;
>  	struct device_node *node;
>  };
>  
> +
Empty line.

>  /**
>   * struct mipi_dsi_device - DSI peripheral device
>   * @host: DSI host for this peripheral
>   * @dev: driver model device node for this peripheral
> + * @name: name of the dsi peripheral
>   * @channel: virtual channel assigned to the peripheral
>   * @format: pixel format for video mode
>   * @lanes: number of active data lanes
> @@ -165,6 +171,8 @@ struct mipi_dsi_device {
>  	struct mipi_dsi_host *host;
>  	struct device dev;
>  
> +	char name[DSI_DEV_NAME_SIZE];
> +
This empty line can be also removed.

Regards
Andrzej

>  	unsigned int channel;
>  	unsigned int lanes;
>  	enum mipi_dsi_pixel_format format;