From: Marek Vasut <marex@denx.de>
To: linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] video: mxsfb: Fix colors display on lower color depth
Date: Thu, 18 Apr 2013 14:00:27 +0000 [thread overview]
Message-ID: <201304181600.27813.marex@denx.de> (raw)
In-Reply-To: <1366277032-671-1-git-send-email-maxime.ripard@free-electrons.com>
Dear Maxime Ripard,
> The current code always registers as a 32 bits display, and uses the
> hardware to drop the MSB of each color to abjust to the interface width
> used by the panel.
>
> This results on 18 bits (and probably 16 bits display as well) in colors
> being displayed poorly, because the MSB are obviously the most important
> bits for each color definition.
>
> The default controller behaviour when using an interface width smaller
> than the color depth is to drop the LSBs of each color, which makes more
> sense because you lose the least important part of the color definition.
>
> So, to fix the colors display, just get back to the default controller
> behaviour.
>
> Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Isn't this what M28EVK is doing already? This was last tested on 3.9-rc3 I
think:
bits-per-pixel = <16>;
bus-width = <18>;
But it's also true we have all 24 data lines routed to the LCD.
Best regards,
Marek Vasut
WARNING: multiple messages have this Message-ID (diff)
From: marex@denx.de (Marek Vasut)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] video: mxsfb: Fix colors display on lower color depth
Date: Thu, 18 Apr 2013 16:00:27 +0200 [thread overview]
Message-ID: <201304181600.27813.marex@denx.de> (raw)
In-Reply-To: <1366277032-671-1-git-send-email-maxime.ripard@free-electrons.com>
Dear Maxime Ripard,
> The current code always registers as a 32 bits display, and uses the
> hardware to drop the MSB of each color to abjust to the interface width
> used by the panel.
>
> This results on 18 bits (and probably 16 bits display as well) in colors
> being displayed poorly, because the MSB are obviously the most important
> bits for each color definition.
>
> The default controller behaviour when using an interface width smaller
> than the color depth is to drop the LSBs of each color, which makes more
> sense because you lose the least important part of the color definition.
>
> So, to fix the colors display, just get back to the default controller
> behaviour.
>
> Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Isn't this what M28EVK is doing already? This was last tested on 3.9-rc3 I
think:
bits-per-pixel = <16>;
bus-width = <18>;
But it's also true we have all 24 data lines routed to the LCD.
Best regards,
Marek Vasut
WARNING: multiple messages have this Message-ID (diff)
From: Marek Vasut <marex@denx.de>
To: Maxime Ripard <maxime.ripard@free-electrons.com>
Cc: Shawn Guo <shawn.guo@linaro.org>,
linux-arm-kernel@lists.infradead.org,
Fabio Estevam <fabio.estevam@freescale.com>,
Alexandre Belloni <alexandre.belloni@free-electrons.com>,
Thomas Petazzoni <thomas@free-electrons.com>,
Brian Lilly <brian@crystalfontz.com>,
Florian Tobias Schandinat <FlorianSchandinat@gmx.de>,
linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] video: mxsfb: Fix colors display on lower color depth
Date: Thu, 18 Apr 2013 16:00:27 +0200 [thread overview]
Message-ID: <201304181600.27813.marex@denx.de> (raw)
In-Reply-To: <1366277032-671-1-git-send-email-maxime.ripard@free-electrons.com>
Dear Maxime Ripard,
> The current code always registers as a 32 bits display, and uses the
> hardware to drop the MSB of each color to abjust to the interface width
> used by the panel.
>
> This results on 18 bits (and probably 16 bits display as well) in colors
> being displayed poorly, because the MSB are obviously the most important
> bits for each color definition.
>
> The default controller behaviour when using an interface width smaller
> than the color depth is to drop the LSBs of each color, which makes more
> sense because you lose the least important part of the color definition.
>
> So, to fix the colors display, just get back to the default controller
> behaviour.
>
> Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Isn't this what M28EVK is doing already? This was last tested on 3.9-rc3 I
think:
bits-per-pixel = <16>;
bus-width = <18>;
But it's also true we have all 24 data lines routed to the LCD.
Best regards,
Marek Vasut
next prev parent reply other threads:[~2013-04-18 14:00 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-17 15:15 MXS framebuffer driver and 18bits display Maxime Ripard
2013-04-18 9:23 ` [PATCH] video: mxsfb: Fix colors display on lower color depth Maxime Ripard
2013-04-18 9:23 ` Maxime Ripard
2013-04-18 9:23 ` Maxime Ripard
2013-04-18 14:00 ` Marek Vasut [this message]
2013-04-18 14:00 ` Marek Vasut
2013-04-18 14:00 ` Marek Vasut
2013-04-18 14:48 ` Shawn Guo
2013-04-18 14:48 ` Shawn Guo
2013-04-18 14:48 ` Shawn Guo
2013-04-22 8:07 ` Maxime Ripard
2013-04-22 8:07 ` Maxime Ripard
2013-04-22 8:07 ` Maxime Ripard
2013-04-18 14:47 ` MXS framebuffer driver and 18bits display Shawn Guo
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