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

From: Greg KH <gregkh@linuxfoundation.org>
To: Max Staudt <mstaudt@suse.de>
Cc: pjones@redhat.com, plagnioj@jcrosoft.com, tomi.valkeinen@ti.com,
	eich@suse.de, tiwai@suse.de, agraf@suse.de,
	linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	stable@vger.kernel.org
Subject: Re: [PATCH] [efifb] Fix 16 color palette entry calculation
Date: Tue, 7 Jun 2016 09:41:50 -0700	[thread overview]
Message-ID: <20160607164150.GC24455@kroah.com> (raw)
In-Reply-To: <1465307143-21398-1-git-send-email-mstaudt@suse.de>

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@suse.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>