[PATCH 5/9] drm/ast: dp501: Use struct drm_edid and helpers

[Thomas Zimmermann]

Hi

Am 09.08.24 um 13:36 schrieb Jocelyn Falempe:
>
>
> On 06/08/2024 14:52, Thomas Zimmermann wrote:
>> Convert DP501 support to struct drm_edid and its helpers. Simplifies
>> and modernizes the EDID handling.
>>
>> The driver reads 4 bytes at once, but the overall read length is now
>> variable. Therefore update the EDID read loop to never return more than
>> the requested bytes.
>
> Thanks for this patch.
> I don't have a hardware to test, but I think it may break the EDID 
> reading.

Unfortunately, I don't have the hardware either and I've not even found 
something that would use this code.

>
>>
>> Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
>> ---
>>   drivers/gpu/drm/ast/ast_dp501.c | 92 ++++++++++++++++++++-------------
>>   1 file changed, 55 insertions(+), 37 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/ast/ast_dp501.c 
>> b/drivers/gpu/drm/ast/ast_dp501.c
>> index 478efa226170..1c5a4902d4c2 100644
>> --- a/drivers/gpu/drm/ast/ast_dp501.c
>> +++ b/drivers/gpu/drm/ast/ast_dp501.c
>> @@ -318,32 +318,63 @@ static bool ast_dp501_is_connected(struct 
>> ast_device *ast)
>>       return true;
>>   }
>>   -static bool ast_dp501_read_edid(struct drm_device *dev, u8 *ediddata)
>> +static int ast_dp512_read_edid_block(void *data, u8 *buf, unsigned 
>> int block, size_t len)
>>   {
>> -    struct ast_device *ast = to_ast_device(dev);
>> -    u32 i, boot_address, offset, data;
>> -    u32 *pEDIDidx;
>> +    struct ast_device *ast = data;
>> +    u32 i, boot_address, offset, ediddata;
>>   -    if (!ast_dp501_is_connected(ast))
>> -        return false;
>> +    if (block > (512 / EDID_LENGTH))
>> +        return -EIO;
>> +
>> +    offset = AST_DP501_EDID_DATA + block * EDID_LENGTH;
>>         if (ast->config_mode == ast_use_p2a) {
>>           boot_address = get_fw_base(ast);
>>   -        /* Read EDID */
>> -        offset = AST_DP501_EDID_DATA;
>> -        for (i = 0; i < 128; i += 4) {
>> -            data = ast_mindwm(ast, boot_address + offset + i);
>> -            pEDIDidx = (u32 *)(ediddata + i);
>> -            *pEDIDidx = data;
>> +        for (i = 0; i < len; i += 4) {

Here, i need to round up len to a multiple of 4.

>> +            ediddata = ast_mindwm(ast, boot_address + offset + i);
>
> I think "i" is always a multiple of 4, so the switch case is broken, 
> and will always go to case 0, so reading only 1 byte every 4 bytes ?

Right, what I want is ((len - i) % 4),  so that i get the remaining 
bytes to read.

Best regards
Thomas

>
>> +
>> +            switch (i % 4) {
>> +            case 3:
>> +                *buf = (ediddata >> 24) & 0xff;
>> +                ++buf;
>> +                fallthrough;
>> +            case 2:
>> +                *buf = (ediddata >> 16) & 0xff;
>> +                ++buf;
>> +                fallthrough;
>> +            case 1:
>> +                *buf = (ediddata >> 8) & 0xff;
>> +                ++buf;
>> +                fallthrough;
>> +            case 0:
>> +                *buf = (ediddata) & 0xff;
>> +                ++buf;
>> +                break;
>> +            }
>>           }
>>       } else {
>> -        /* Read EDID */
>> -        offset = AST_DP501_EDID_DATA;
>> -        for (i = 0; i < 128; i += 4) {
>> -            data = readl(ast->dp501_fw_buf + offset + i);
>> -            pEDIDidx = (u32 *)(ediddata + i);
>> -            *pEDIDidx = data;
>> +        for (i = 0; i < len; i += 4) {
>> +            ediddata = readl(ast->dp501_fw_buf + offset + i);
>> +
>> +            switch (i % 4) {
>> +            case 3:
>> +                *buf = (ediddata >> 24) & 0xff;
>> +                ++buf;
>> +                fallthrough;
>> +            case 2:
>> +                *buf = (ediddata >> 16) & 0xff;
>> +                ++buf;
>> +                fallthrough;
>> +            case 1:
>> +                *buf = (ediddata >> 8) & 0xff;
>> +                ++buf;
>> +                fallthrough;
>> +            case 0:
>> +                *buf = (ediddata) & 0xff;
>> +                ++buf;
>> +                break;
>> +            }
>>           }
>>       }
>>   @@ -511,29 +542,16 @@ static const struct drm_encoder_helper_funcs 
>> ast_dp501_encoder_helper_funcs = {
>>     static int ast_dp501_connector_helper_get_modes(struct 
>> drm_connector *connector)
>>   {
>> -    void *edid;
>> -    bool succ;
>> +    struct ast_device *ast = to_ast_device(connector->dev);
>> +    const struct drm_edid *drm_edid;
>>       int count;
>>   -    edid = kmalloc(EDID_LENGTH, GFP_KERNEL);
>> -    if (!edid)
>> -        goto err_drm_connector_update_edid_property;
>> -
>> -    succ = ast_dp501_read_edid(connector->dev, edid);
>> -    if (!succ)
>> -        goto err_kfree;
>> -
>> -    drm_connector_update_edid_property(connector, edid);
>> -    count = drm_add_edid_modes(connector, edid);
>> -    kfree(edid);
>> +    drm_edid = drm_edid_read_custom(connector, 
>> ast_dp512_read_edid_block, ast);
>> +    drm_edid_connector_update(connector, drm_edid);
>> +    count = drm_edid_connector_add_modes(connector);
>> +    drm_edid_free(drm_edid);
>>         return count;
>> -
>> -err_kfree:
>> -    kfree(edid);
>> -err_drm_connector_update_edid_property:
>> -    drm_connector_update_edid_property(connector, NULL);
>> -    return 0;
>>   }
>>     static int ast_dp501_connector_helper_detect_ctx(struct 
>> drm_connector *connector,
>

-- 
--
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)