linux-kernel - Re: [PATCH] [efifb] Fix 16 color palette entry calculation

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Date:	Tue, 7 Jun 2016 09:41:50 -0700
From:	Greg KH <gregkh@...uxfoundation.org>
To:	Max Staudt <mstaudt@...e.de>
Cc:	pjones@...hat.com, plagnioj@...osoft.com, tomi.valkeinen@...com,
	eich@...e.de, tiwai@...e.de, agraf@...e.de,
	linux-fbdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Subject: Re: [PATCH] [efifb] Fix 16 color palette entry calculation

On Tue, Jun 07, 2016 at 03:45:43PM +0200, Max Staudt wrote:
> When using efifb with a 16-bit (5:6:5) visual, fbcon's text is rendered
> in the wrong colors - e.g. text gray (#aaaaaa) is rendered as green
> (#50bc50) and neighboring pixels have slightly different values
> (such as #50bc78).
> 
> The reason is that fbcon loads its 16 color palette through
> efifb_setcolreg(), which in turn calculates a 32-bit value to write
> into memory for each palette index.
> Until now, this code could only handle 8-bit visuals and didn't mask
> overlapping values when ORing them.
> 
> With this patch, fbcon displays the correct colors when a qemu VM is
> booted in 16-bit mode (in GRUB: "set gfxpayload=800x600x16").
> 
> Signed-off-by: Max Staudt <mstaudt@...e.de>
> ---
>  drivers/video/fbdev/efifb.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 

<formletter>

This is not the correct way to submit patches for inclusion in the
stable kernel tree.  Please read Documentation/stable_kernel_rules.txt
for how to do this properly.

</formletter>