This is used to specify the page start address offset of the display RAM.
The value is used as offset when setting the page start address with the
SSD130X_SET_PAGE_RANGE command, and the driver currently sets its value to
1 if the property is not present in the Device Tree.
But the datasheet mentions that the value on reset for the page start is a
0, so it makes more sense to also have 0 as the default value for the page
offset if the property is not present.
In fact, using a default value of 1 leads to the display not working when
the fbdev is attached to the framebuffer console.
Reported-by: Sahaj Sarup <[email protected]>
Signed-off-by: Javier Martinez Canillas <[email protected]>
---
drivers/video/fbdev/ssd1307fb.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/video/fbdev/ssd1307fb.c b/drivers/video/fbdev/ssd1307fb.c
index 5ae48e36fccb..34f014bf4994 100644
--- a/drivers/video/fbdev/ssd1307fb.c
+++ b/drivers/video/fbdev/ssd1307fb.c
@@ -637,7 +637,7 @@ static int ssd1307fb_probe(struct i2c_client *client)
par->height = 16;
if (device_property_read_u32(dev, "solomon,page-offset", &par->page_offset))
- par->page_offset = 1;
+ par->page_offset = 0;
if (device_property_read_u32(dev, "solomon,col-offset", &par->col_offset))
par->col_offset = 0;
--
2.41.0
On Thu, Nov 16, 2023 at 07:07:38PM +0100, Javier Martinez Canillas wrote:
> This is used to specify the page start address offset of the display RAM.
>
> The value is used as offset when setting the page start address with the
> SSD130X_SET_PAGE_RANGE command, and the driver currently sets its value to
> 1 if the property is not present in the Device Tree.
>
> But the datasheet mentions that the value on reset for the page start is a
> 0, so it makes more sense to also have 0 as the default value for the page
> offset if the property is not present.
>
> In fact, using a default value of 1 leads to the display not working when
> the fbdev is attached to the framebuffer console.
>
> Reported-by: Sahaj Sarup <[email protected]>
Closes?
Fixes?
> Signed-off-by: Javier Martinez Canillas <[email protected]>
--
With Best Regards,
Andy Shevchenko
Andy Shevchenko <[email protected]> writes:
Hello Andy,
> On Thu, Nov 16, 2023 at 07:07:38PM +0100, Javier Martinez Canillas wrote:
>> This is used to specify the page start address offset of the display RAM.
>>
>> The value is used as offset when setting the page start address with the
>> SSD130X_SET_PAGE_RANGE command, and the driver currently sets its value to
>> 1 if the property is not present in the Device Tree.
>>
>> But the datasheet mentions that the value on reset for the page start is a
>> 0, so it makes more sense to also have 0 as the default value for the page
>> offset if the property is not present.
>>
>> In fact, using a default value of 1 leads to the display not working when
>> the fbdev is attached to the framebuffer console.
>>
>> Reported-by: Sahaj Sarup <[email protected]>
>
> Closes?
There's no report in a mailing list or bug tracker to reference.
> Fixes?
>
Since the default has been the same since the driver was merged,
it doesn't make that much sense for me to reference that commit.
--
Best regards,
Javier Martinez Canillas
Core Platforms
Red Hat