linux-kernel - [PATCH 2/3] fbdev: ssd1307fb: Change "solomon,page-offset" property default value

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Message-ID: <20231116180743.2763021-2-javierm@redhat.com>
Date:   Thu, 16 Nov 2023 19:07:38 +0100
From:   Javier Martinez Canillas <javierm@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     Sahaj Sarup <sahaj.sarup@...aro.org>,
        Javier Martinez Canillas <javierm@...hat.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Helge Deller <deller@....de>, Sam Ravnborg <sam@...nborg.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>, dri-devel@...ts.freedesktop.org,
        linux-fbdev@...r.kernel.org
Subject: [PATCH 2/3] fbdev: ssd1307fb: Change "solomon,page-offset" property default value

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 <sahaj.sarup@...aro.org>
Signed-off-by: Javier Martinez Canillas <javierm@...hat.com>
---

 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