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

[Jani Nikula <jani.nikula@intel.com>]

On Mon, 08 Apr 2024, Ville Syrjälä <ville.syrjala@linux.intel.com> wrote:
> 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.

Agreed.

>
>> +		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"? 

Agreed.

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

Refactored using struct seq_buf and a helper function; v2 out shortly.

BR,
Jani.

>
>> +				 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

-- 
Jani Nikula, Intel