[PATCH v2 02/10] drm/bochs: Use helpers for struct drm_edid

[Thomas Zimmermann]

Hi

Am 23.09.24 um 06:35 schrieb Dmitry Baryshkov:
> On Mon, Sep 02, 2024 at 12:53:40PM GMT, Thomas Zimmermann wrote:
>> Implement a read function for struct drm_edid and read the EDID data
>> with drm_edit_read_custom(). Update the connector data accordingly.
>>
>> The EDID data comes from the emulator itself and the connector stores
>> a copy in its EDID property. The drm_edid field in struct bochs_device
>> is therefore not required. Remove it.
>>
>> If qemu provides no EDID data, install default display modes as before.
>>
>> Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
>> Acked-by: Gerd Hoffmann <kraxel at redhat.com>
>> ---
>>   drivers/gpu/drm/tiny/bochs.c | 48 +++++++++++++++++-------------------
>>   1 file changed, 22 insertions(+), 26 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/tiny/bochs.c b/drivers/gpu/drm/tiny/bochs.c
>> index 47a45a14306c..197fc00b373f 100644
>> --- a/drivers/gpu/drm/tiny/bochs.c
>> +++ b/drivers/gpu/drm/tiny/bochs.c
>> @@ -85,7 +85,6 @@ struct bochs_device {
>>   	u16 yres_virtual;
>>   	u32 stride;
>>   	u32 bpp;
>> -	const struct drm_edid *drm_edid;
>>   
>>   	/* drm */
>>   	struct drm_device *dev;
>> @@ -172,12 +171,14 @@ static void bochs_hw_set_little_endian(struct bochs_device *bochs)
>>   #define bochs_hw_set_native_endian(_b) bochs_hw_set_little_endian(_b)
>>   #endif
>>   
>> -static int bochs_get_edid_block(void *data, u8 *buf,
>> -				unsigned int block, size_t len)
>> +static int bochs_get_edid_block(void *data, u8 *buf, unsigned int block, size_t len)
>>   {
>>   	struct bochs_device *bochs = data;
>>   	size_t i, start = block * EDID_LENGTH;
>>   
>> +	if (!bochs->mmio)
>> +		return -1;
>> +
>>   	if (start + len > 0x400 /* vga register offset */)
>>   		return -1;
>>   
>> @@ -187,25 +188,20 @@ static int bochs_get_edid_block(void *data, u8 *buf,
>>   	return 0;
>>   }
>>   
>> -static int bochs_hw_load_edid(struct bochs_device *bochs)
>> +static const struct drm_edid *bochs_hw_read_edid(struct drm_connector *connector)
>>   {
>> +	struct drm_device *dev = connector->dev;
>> +	struct bochs_device *bochs = dev->dev_private;
>>   	u8 header[8];
>>   
>> -	if (!bochs->mmio)
>> -		return -1;
>> -
>>   	/* check header to detect whenever edid support is enabled in qemu */
>>   	bochs_get_edid_block(bochs, header, 0, ARRAY_SIZE(header));
>>   	if (drm_edid_header_is_valid(header) != 8)
> I understand that you probably don't want to change the behaviour of the
> driver, but maybe it's better to check drm_edid_read_custom return
> value? Bochs, amdgpu and radeon are the only drivers that call
> drm_edid_header_is_valid().

The nearby comment indicates that EDID support might not be present in 
qemu. But drm_edid_read_custom() warns in this case, even though it's a 
legal state. Hence the test.

Best regards
Thomas

>
>> -		return -1;
>> +		return NULL;
>>   

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)