[PATCH] fbdev: ssd1307fb: return proper error code if write command fails

[PATCH] fbdev: ssd1307fb: return proper error code if write command fails

[Lad, Prabhakar]

this patch fixes ssd1307fb_ssd1306_init() function to return
proper error codes in case of failures.

Signed-off-by: Lad, Prabhakar <prabhakar.csengg@gmail.com>
---
 drivers/video/fbdev/ssd1307fb.c | 54 ++++++++++++++++++++++++++++++-----------
 1 file changed, 40 insertions(+), 14 deletions(-)

diff --git a/drivers/video/fbdev/ssd1307fb.c b/drivers/video/fbdev/ssd1307fb.c
index f4daa59..528ea16 100644
--- a/drivers/video/fbdev/ssd1307fb.c
+++ b/drivers/video/fbdev/ssd1307fb.c
@@ -320,7 +320,9 @@ static int ssd1307fb_ssd1306_init(struct ssd1307fb_par *par)
 
 	/* Set initial contrast */
 	ret = ssd1307fb_write_cmd(par->client, SSD1307FB_CONTRAST);
-	ret = ret & ssd1307fb_write_cmd(par->client, 0x7f);
+	if (ret < 0)
+		return ret;
+	ret = ssd1307fb_write_cmd(par->client, 0x7f);
 	if (ret < 0)
 		return ret;
 
@@ -336,63 +338,87 @@ static int ssd1307fb_ssd1306_init(struct ssd1307fb_par *par)
 
 	/* Set multiplex ratio value */
 	ret = ssd1307fb_write_cmd(par->client, SSD1307FB_SET_MULTIPLEX_RATIO);
-	ret = ret & ssd1307fb_write_cmd(par->client, par->height - 1);
+	if (ret < 0)
+		return ret;
+	ret = ssd1307fb_write_cmd(par->client, par->height - 1);
 	if (ret < 0)
 		return ret;
 
 	/* set display offset value */
 	ret = ssd1307fb_write_cmd(par->client, SSD1307FB_SET_DISPLAY_OFFSET);
+	if (ret < 0)
+		return ret;
 	ret = ssd1307fb_write_cmd(par->client, 0x20);
 	if (ret < 0)
 		return ret;
 
 	/* Set clock frequency */
 	ret = ssd1307fb_write_cmd(par->client, SSD1307FB_SET_CLOCK_FREQ);
-	ret = ret & ssd1307fb_write_cmd(par->client, 0xf0);
+	if (ret < 0)
+		return ret;
+	ret = ssd1307fb_write_cmd(par->client, 0xf0);
 	if (ret < 0)
 		return ret;
 
 	/* Set precharge period in number of ticks from the internal clock */
 	ret = ssd1307fb_write_cmd(par->client, SSD1307FB_SET_PRECHARGE_PERIOD);
-	ret = ret & ssd1307fb_write_cmd(par->client, 0x22);
+	if (ret < 0)
+		return ret;
+	ret = ssd1307fb_write_cmd(par->client, 0x22);
 	if (ret < 0)
 		return ret;
 
 	/* Set COM pins configuration */
 	ret = ssd1307fb_write_cmd(par->client, SSD1307FB_SET_COM_PINS_CONFIG);
-	ret = ret & ssd1307fb_write_cmd(par->client, 0x22);
+	if (ret < 0)
+		return ret;
+	ret = ssd1307fb_write_cmd(par->client, 0x22);
 	if (ret < 0)
 		return ret;
 
 	/* Set VCOMH */
 	ret = ssd1307fb_write_cmd(par->client, SSD1307FB_SET_VCOMH);
-	ret = ret & ssd1307fb_write_cmd(par->client, 0x49);
+	if (ret < 0)
+		return ret;
+	ret = ssd1307fb_write_cmd(par->client, 0x49);
 	if (ret < 0)
 		return ret;
 
 	/* Turn on the DC-DC Charge Pump */
 	ret = ssd1307fb_write_cmd(par->client, SSD1307FB_CHARGE_PUMP);
-	ret = ret & ssd1307fb_write_cmd(par->client, 0x14);
+	if (ret < 0)
+		return ret;
+	ret = ssd1307fb_write_cmd(par->client, 0x14);
 	if (ret < 0)
 		return ret;
 
 	/* Switch to horizontal addressing mode */
 	ret = ssd1307fb_write_cmd(par->client, SSD1307FB_SET_ADDRESS_MODE);
-	ret = ret & ssd1307fb_write_cmd(par->client,
-					SSD1307FB_SET_ADDRESS_MODE_HORIZONTAL);
+	if (ret < 0)
+		return ret;
+	ret = ssd1307fb_write_cmd(par->client,
+				  SSD1307FB_SET_ADDRESS_MODE_HORIZONTAL);
 	if (ret < 0)
 		return ret;
 
 	ret = ssd1307fb_write_cmd(par->client, SSD1307FB_SET_COL_RANGE);
-	ret = ret & ssd1307fb_write_cmd(par->client, 0x0);
-	ret = ret & ssd1307fb_write_cmd(par->client, par->width - 1);
+	if (ret < 0)
+		return ret;
+	ret = ssd1307fb_write_cmd(par->client, 0x0);
+	if (ret < 0)
+		return ret;
+	ret = ssd1307fb_write_cmd(par->client, par->width - 1);
 	if (ret < 0)
 		return ret;
 
 	ret = ssd1307fb_write_cmd(par->client, SSD1307FB_SET_PAGE_RANGE);
-	ret = ret & ssd1307fb_write_cmd(par->client, 0x0);
-	ret = ret & ssd1307fb_write_cmd(par->client,
-					par->page_offset + (par->height / 8) - 1);
+	if (ret < 0)
+		return ret;
+	ret = ssd1307fb_write_cmd(par->client, 0x0);
+	if (ret < 0)
+		return ret;
+	ret = ssd1307fb_write_cmd(par->client,
+				  par->page_offset + (par->height / 8) - 1);
 	if (ret < 0)
 		return ret;
 
-- 
1.9.1

Re: [PATCH] fbdev: ssd1307fb: return proper error code if write command fails

[Maxime Ripard]

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Hi,

Thanks for doing this,

On Wed, Jan 14, 2015 at 08:24:49AM +0000, Lad, Prabhakar wrote:
> this patch fixes ssd1307fb_ssd1306_init() function to return
> proper error codes in case of failures.
> 
> Signed-off-by: Lad, Prabhakar <prabhakar.csengg@gmail.com>
> ---
>  drivers/video/fbdev/ssd1307fb.c | 54 ++++++++++++++++++++++++++++++-----------
>  1 file changed, 40 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/video/fbdev/ssd1307fb.c b/drivers/video/fbdev/ssd1307fb.c
> index f4daa59..528ea16 100644
> --- a/drivers/video/fbdev/ssd1307fb.c
> +++ b/drivers/video/fbdev/ssd1307fb.c
> @@ -320,7 +320,9 @@ static int ssd1307fb_ssd1306_init(struct ssd1307fb_par *par)
>  
>  	/* Set initial contrast */
>  	ret = ssd1307fb_write_cmd(par->client, SSD1307FB_CONTRAST);
> -	ret = ret & ssd1307fb_write_cmd(par->client, 0x7f);
> +	if (ret < 0)
> +		return ret;

A newline here (and to all the subsequent changes) would be great.

Thanks!
Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

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