Re: [PATCH 01/15] video: fbdev: atmel_lcdfb: Rework backlight handling

From: Stephen Kitt <steve@sk2.org>
To: sam@ravnborg.org,
	Sam Ravnborg via B4 Submission Endpoint
	<devnull+sam.ravnborg.org@kernel.org>,
	Nicolas Ferre <nicolas.ferre@microchip.com>,
	Helge Deller <deller@gmx.de>,
	Alexandre Belloni <alexandre.belloni@bootlin.com>,
	Claudiu Beznea <claudiu.beznea@microchip.com>,
	Antonino Daplas <adaplas@gmail.com>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Robin van der Gracht <robin@protonic.nl>,
	Miguel Ojeda <ojeda@kernel.org>, Lee Jones <lee@kernel.org>,
	Daniel Thompson <daniel.thompson@linaro.org>,
	Jingoo Han <jingoohan1@gmail.com>
Cc: linux-fbdev@vger.kernel.org, dri-devel@lists.freedesktop.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, linux-omap@vger.kernel.org,
	linux-staging@lists.linux.dev, linuxppc-dev@lists.ozlabs.org,
	Sam Ravnborg <sam@ravnborg.org>,
	Ludovic Desroches <ludovic.desroches@microchip.com>
Subject: Re: [PATCH 01/15] video: fbdev: atmel_lcdfb: Rework backlight handling
Date: Sat, 07 Jan 2023 21:36:47 +0100	[thread overview]
Message-ID: <553AE999-CAF1-4E59-9F3F-68591ED192DE@sk2.org> (raw)
In-Reply-To: <20230107-sam-video-backlight-drop-fb_blank-v1-1-1bd9bafb351f@ravnborg.org>

On 7 January 2023 19:26:15 CET, Sam Ravnborg via B4 Submission Endpoint <devnull+sam.ravnborg.org@kernel.org> wrote:
>From: Sam Ravnborg <sam@ravnborg.org>
>
>The atmel_lcdfb had code to save/restore power state.
>This is not needed so drop it.
>
>Introduce backlight_is_brightness() to make logic simpler.
>
>Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
>Cc: Nicolas Ferre <nicolas.ferre@microchip.com>
>Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>
>Cc: Ludovic Desroches <ludovic.desroches@microchip.com>
>Cc: linux-fbdev@vger.kernel.org
>Cc: linux-arm-kernel@lists.infradead.org
>---
> drivers/video/fbdev/atmel_lcdfb.c | 24 +++---------------------
> 1 file changed, 3 insertions(+), 21 deletions(-)
>
>diff --git a/drivers/video/fbdev/atmel_lcdfb.c b/drivers/video/fbdev/atmel_lcdfb.c
>index 1fc8de4ecbeb..d297b3892637 100644
>--- a/drivers/video/fbdev/atmel_lcdfb.c
>+++ b/drivers/video/fbdev/atmel_lcdfb.c
>@@ -49,7 +49,6 @@ struct atmel_lcdfb_info {
> 	struct clk		*lcdc_clk;
> 
> 	struct backlight_device	*backlight;
>-	u8			bl_power;
> 	u8			saved_lcdcon;
> 
> 	u32			pseudo_palette[16];
>@@ -109,32 +108,18 @@ static u32 contrast_ctr = ATMEL_LCDC_PS_DIV8
> static int atmel_bl_update_status(struct backlight_device *bl)
> {
> 	struct atmel_lcdfb_info *sinfo = bl_get_data(bl);
>-	int			power = sinfo->bl_power;
>-	int			brightness = bl->props.brightness;
>+	int brightness;
> 
>-	/* REVISIT there may be a meaningful difference between
>-	 * fb_blank and power ... there seem to be some cases
>-	 * this doesn't handle correctly.
>-	 */
>-	if (bl->props.fb_blank != sinfo->bl_power)
>-		power = bl->props.fb_blank;
>-	else if (bl->props.power != sinfo->bl_power)
>-		power = bl->props.power;
>-
>-	if (brightness < 0 && power == FB_BLANK_UNBLANK)
>-		brightness = lcdc_readl(sinfo, ATMEL_LCDC_CONTRAST_VAL);
>-	else if (power != FB_BLANK_UNBLANK)
>-		brightness = 0;
>+	brightness = backlight_get_brightness(bl);
> 
> 	lcdc_writel(sinfo, ATMEL_LCDC_CONTRAST_VAL, brightness);
>+
> 	if (contrast_ctr & ATMEL_LCDC_POL_POSITIVE)
> 		lcdc_writel(sinfo, ATMEL_LCDC_CONTRAST_CTR,
> 			brightness ? contrast_ctr : 0);
> 	else
> 		lcdc_writel(sinfo, ATMEL_LCDC_CONTRAST_CTR, contrast_ctr);
> 
>-	bl->props.fb_blank = bl->props.power = sinfo->bl_power = power;
>-
> 	return 0;
> }
> 
>@@ -155,8 +140,6 @@ static void init_backlight(struct atmel_lcdfb_info *sinfo)
> 	struct backlight_properties props;
> 	struct backlight_device	*bl;
> 
>-	sinfo->bl_power = FB_BLANK_UNBLANK;
>-
> 	if (sinfo->backlight)
> 		return;
> 
>@@ -173,7 +156,6 @@ static void init_backlight(struct atmel_lcdfb_info *sinfo)
> 	sinfo->backlight = bl;
> 
> 	bl->props.power = FB_BLANK_UNBLANK;
>-	bl->props.fb_blank = FB_BLANK_UNBLANK;
> 	bl->props.brightness = atmel_bl_get_brightness(bl);
> }
> 
>

Hi Sam,

I’d submitted quite a few more of these previously (and you’d reviewed them), see e.g. the thread starting at https://lkml.org/lkml/2022/6/7/4365, and yesterday, https://lkml.org/lkml/2023/1/6/520, https://lkml.org/lkml/2023/1/6/656, https://lkml.org/lkml/2023/1/6/970, https://lkml.org/lkml/2023/1/6/643, and https://lkml.org/lkml/2023/1/6/680. There are a few more, I can find them if it’s any use.

Regards,

Stephen