# \[PATCH\] \[efifb\] Fix 16 color palette entry calculation - Subsystems: EFIFB FRAMEBUFFER DRIVER, FRAMEBUFFER LAYER, THE REST - Maintainers: Peter Jones, Helge Deller, Linus Torvalds - List: linux-fbdev - 7 messages, 5 authors - Page: https://ratatoskr.run/linux-fbdev/2016/06/4767178/t ## \[PATCH\] \[efifb\] Fix 16 color palette entry calculation - From: Max Staudt \ - Date: 2016-06-07 13:46:23 - Message: https://ratatoskr.run/linux-fbdev/2016/06/4767178.md ```text 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€0x600x16"). Signed-off-by: Max Staudt --- drivers/video/fbdev/efifb.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/video/fbdev/efifb.c b/drivers/video/fbdev/efifb.c index 924bad4..37a37c4 100644 --- a/drivers/video/fbdev/efifb.c +++ b/drivers/video/fbdev/efifb.c @@ -50,9 +50,9 @@ static int efifb_setcolreg(unsigned regno, unsigned red, unsigned green, return 1; if (regno < 16) { - red >>= 8; - green >>= 8; - blue >>= 8; + red >>= 16 - info->var.red.length; + green >>= 16 - info->var.green.length; + blue >>= 16 - info->var.blue.length; ((u32 *)(info->pseudo_palette))[regno] (red << info->var.red.offset) | (green << info->var.green.offset) | -- 2.6.6 ``` ## Re: \[PATCH\] \[efifb\] Fix 16 color palette entry calculation - From: Greg KH \ - Date: 2016-06-07 16:41:53 - Message: https://ratatoskr.run/linux-fbdev/2016/06/4767388.md ```text 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€0x600x16"). > > Signed-off-by: Max Staudt > --- > drivers/video/fbdev/efifb.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > 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. ``` ## Re: \[PATCH\] \[efifb\] Fix 16 color palette entry calculation - From: Peter Jones \ - Date: 2016-06-07 17:23:14 - Message: https://ratatoskr.run/linux-fbdev/2016/06/4767422.md ```text 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€0x600x16"). > > Signed-off-by: Max Staudt > --- > drivers/video/fbdev/efifb.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/drivers/video/fbdev/efifb.c b/drivers/video/fbdev/efifb.c > index 924bad4..37a37c4 100644 > --- a/drivers/video/fbdev/efifb.c > +++ b/drivers/video/fbdev/efifb.c > @@ -50,9 +50,9 @@ static int efifb_setcolreg(unsigned regno, unsigned red, unsigned green, > return 1; > > if (regno < 16) { > - red >>= 8; > - green >>= 8; > - blue >>= 8; > + red >>= 16 - info->var.red.length; > + green >>= 16 - info->var.green.length; > + blue >>= 16 - info->var.blue.length; > ((u32 *)(info->pseudo_palette))[regno] > (red << info->var.red.offset) | > (green << info->var.green.offset) | > -- > 2.6.6 Looks right to me. Acked-By: Peter Jones -- Peter ``` ## Re: \[PATCH\] \[efifb\] Fix 16 color palette entry calculation - From: Matt Fleming \ - Date: 2016-06-08 12:43:54 - Message: https://ratatoskr.run/linux-fbdev/2016/06/4768382.md ```text On Tue, 07 Jun, at 01:23:05PM, Peter Jones wrote: > > Looks right to me. > > Acked-By: Peter Jones Tomi, are you OK to take this one or would you like me to take it through the EFI tree? ``` ## Re: \[PATCH\] \[efifb\] Fix 16 color palette entry calculation - From: Tomi Valkeinen \ - Date: 2016-06-10 11:33:30 - Message: https://ratatoskr.run/linux-fbdev/2016/06/4770337.md ```text On 08/06/16 15:43, Matt Fleming wrote: > On Tue, 07 Jun, at 01:23:05PM, Peter Jones wrote: >> >> Looks right to me. >> >> Acked-By: Peter Jones > > Tomi, are you OK to take this one or would you like me to take it > through the EFI tree? I can pick this up, but as Greg said, this is not valid for stable. Max, please resend with correct stable reference. Tomi ``` ## \[PATCH RESEND\] fbdev/efifb: Fix 16 color palette entry calculation - From: Max Staudt \ - Date: 2016-06-13 17:16:16 - Message: https://ratatoskr.run/linux-fbdev/2016/06/4772172.md ```text 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€0x600x16"). Fixes: 7c83172b98e5 ("x86_64 EFI boot support: EFI frame buffer driver") # v2.6.24+ Signed-off-by: Max Staudt Acked-By: Peter Jones Cc: --- drivers/video/fbdev/efifb.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/video/fbdev/efifb.c b/drivers/video/fbdev/efifb.c index 924bad4..37a37c4 100644 --- a/drivers/video/fbdev/efifb.c +++ b/drivers/video/fbdev/efifb.c @@ -50,9 +50,9 @@ static int efifb_setcolreg(unsigned regno, unsigned red, unsigned green, return 1; if (regno < 16) { - red >>= 8; - green >>= 8; - blue >>= 8; + red >>= 16 - info->var.red.length; + green >>= 16 - info->var.green.length; + blue >>= 16 - info->var.blue.length; ((u32 *)(info->pseudo_palette))[regno] (red << info->var.red.offset) | (green << info->var.green.offset) | -- 2.6.6 ``` ## Re: \[PATCH RESEND\] fbdev/efifb: Fix 16 color palette entry calculation - From: Tomi Valkeinen \ - Date: 2016-08-10 19:02:56 - Message: https://ratatoskr.run/linux-fbdev/2016/08/4811400.md ```text On 13/06/16 20:15, 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"). > > Fixes: 7c83172b98e5 ("x86_64 EFI boot support: EFI frame buffer driver") # v2.6.24+ > Signed-off-by: Max Staudt > Acked-By: Peter Jones > Cc: > --- > drivers/video/fbdev/efifb.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) Thanks, queued for v4.9. Tomi ```