Re: [PATCH 2/4] drm/edid: add drm_edid_print_product_id()

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Thu, Mar 21, 2024 at 12:05:10PM +0200, Jani Nikula wrote:
> Add a function to print a decoded EDID vendor and product id to a drm
> printer, optinally with the raw data.
> 
> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
> ---
>  drivers/gpu/drm/drm_edid.c | 35 +++++++++++++++++++++++++++++++++++
>  include/drm/drm_edid.h     |  3 +++
>  2 files changed, 38 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index 626a0e24e66a..198986f0eb8b 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
> @@ -29,6 +29,7 @@
>   */
>  
>  #include <linux/bitfield.h>
> +#include <linux/byteorder/generic.h>
>  #include <linux/cec.h>
>  #include <linux/hdmi.h>
>  #include <linux/i2c.h>
> @@ -2771,6 +2772,40 @@ void drm_edid_get_product_id(const struct drm_edid *drm_edid,
>  }
>  EXPORT_SYMBOL(drm_edid_get_product_id);
>  
> +/**
> + * drm_edid_print_product_id - Print decoded product id to printer
> + * @p: drm printer
> + * @id: EDID product id
> + * @raw: If true, also print the raw hex
> + */
> +void drm_edid_print_product_id(struct drm_printer *p,
> +			       const struct drm_edid_product_id *id, bool raw)
> +{
> +	u16 mfg_id = id->manufacturer_name[0] << 8 | id->manufacturer_name[1];
> +	char *date;
> +	char vend[4];
> +
> +	drm_edid_decode_mfg_id(mfg_id, vend);
> +
> +	if (id->week_of_manufacture == 0xff)

Didn't realize this had a loaded meaning. Maybe we should also
skip the week printout if week==0? Otherwise people might think
week==0 means the first week.

> +		date = kasprintf(GFP_KERNEL, "model year: %d",
> +				 id->year_of_manufacture + 1990);
> +	else
> +		date = kasprintf(GFP_KERNEL, "week: %d, year of manufacture: %d",

The "week: %d" part feels a bit left out here. Maybe this should be
formatted as "week/year of manufacture: %d/%d"? 

Not sure I like the kasprintf(). Maybe use an on-stack buffer?

> +				 id->week_of_manufacture,
> +				 id->year_of_manufacture + 1990);
> +
> +	drm_printf(p, "manufacturer name: %s, product code: %u, serial number: %u, %s\n",
> +		   vend, le16_to_cpu(id->product_code),
> +		   le32_to_cpu(id->serial_number), date ?: "");
> +
> +	if (raw)
> +		drm_printf(p, "raw product id: %*ph\n", (int)sizeof(*id), id);
> +
> +	kfree(date);
> +}
> +EXPORT_SYMBOL(drm_edid_print_product_id);
> +
>  /**
>   * drm_edid_get_panel_id - Get a panel's ID from EDID
>   * @drm_edid: EDID that contains panel ID.
> diff --git a/include/drm/drm_edid.h b/include/drm/drm_edid.h
> index 7911a2f8a672..c763ba1a0bbd 100644
> --- a/include/drm/drm_edid.h
> +++ b/include/drm/drm_edid.h
> @@ -30,6 +30,7 @@ struct drm_connector;
>  struct drm_device;
>  struct drm_display_mode;
>  struct drm_edid;
> +struct drm_printer;
>  struct hdmi_avi_infoframe;
>  struct hdmi_vendor_infoframe;
>  struct i2c_adapter;
> @@ -481,6 +482,8 @@ int drm_edid_connector_add_modes(struct drm_connector *connector);
>  bool drm_edid_is_digital(const struct drm_edid *drm_edid);
>  void drm_edid_get_product_id(const struct drm_edid *drm_edid,
>  			     struct drm_edid_product_id *id);
> +void drm_edid_print_product_id(struct drm_printer *p,
> +			       const struct drm_edid_product_id *id, bool raw);
>  
>  const u8 *drm_find_edid_extension(const struct drm_edid *drm_edid,
>  				  int ext_id, int *ext_index);
> -- 
> 2.39.2

-- 
Ville Syrjälä
Intel