[PATCH] fbdev/ffb: fix corrupted video output on FFB1

[PATCH] fbdev/ffb: fix corrupted video output on FFB1

[René Rebe]

Fix Sun FFB1 corrupted video out [1] by disabling overlay and
initializing window mode to a known state. The issue never appeared on
my FFB2+/vertical nor Elite3D/M6. It could also depend on the PROM
version.

/SUNW,ffb@1e,0: FFB at 000001fc00000000, type 11, DAC pnum[236c] rev[10] manuf_rev[4]
X (II) /dev/fb0: Detected FFB1, Z-buffer, Single-buffered.
X (II) /dev/fb0: BT9068 (PAC1) ramdac detected (with normal cursor control)
X (II) /dev/fb0: Detected Creator/Creator3D

[1] https://www.instagram.com/p/DUTcSmSjSem/

Signed-off-by: René Rebe <rene@exactco.de>
Cc: stable@kernel.org
---
Tested on Sun Ultra 2 w/ FFB1 BT9068 (PAC1) ramdac running T2/Linux.
Defines re-used from xf86-video-sunffb.
---
diff --git a/drivers/video/fbdev/ffb.c b/drivers/video/fbdev/ffb.c
index 34b6abff9493..8d77f102dd82 100644
--- a/drivers/video/fbdev/ffb.c
+++ b/drivers/video/fbdev/ffb.c
@@ -335,6 +335,9 @@ struct ffb_dac {
 };
 
 #define FFB_DAC_UCTRL		0x1001 /* User Control */
+#define FFB_DAC_UCTRL_OVENAB	0x00000008 /* Overlay Enable */
+#define FFB_DAC_UCTRL_WMODE	0x00000030 /* Window Mode */
+#define FFB_DAC_UCTRL_WM_COMB	0x00000000 /* Window Mode = Combined */
 #define FFB_DAC_UCTRL_MANREV	0x00000f00 /* 4-bit Manufacturing Revision */
 #define FFB_DAC_UCTRL_MANREV_SHIFT 8
 #define FFB_DAC_TGEN		0x6000 /* Timing Generator */
@@ -425,7 +428,7 @@ static void ffb_switch_from_graph(struct ffb_par *par)
 {
 	struct ffb_fbc __iomem *fbc = par->fbc;
 	struct ffb_dac __iomem *dac = par->dac;
-	unsigned long flags;
+	unsigned long flags, uctrl;
 
 	spin_lock_irqsave(&par->lock, flags);
 	FFBWait(par);
@@ -442,7 +445,7 @@ static void ffb_switch_from_graph(struct ffb_par *par)
 	upa_writel(par->bg_cache, &fbc->bg);
 	FFBWait(par);
 
-	/* Disable cursor.  */
+	/* Disable cursor. */
 	upa_writel(FFB_DAC_CUR_CTRL, &dac->type2);
 	if (par->flags & FFB_FLAG_INVCURSOR)
 		upa_writel(0, &dac->value2);
@@ -450,6 +453,15 @@ static void ffb_switch_from_graph(struct ffb_par *par)
 		upa_writel((FFB_DAC_CUR_CTRL_P0 |
 			    FFB_DAC_CUR_CTRL_P1), &dac->value2);
 
+	/* Disable overlay and window modes. */
+	upa_writel(FFB_DAC_UCTRL, &dac->type);
+	uctrl = upa_readl(&dac->value);
+	uctrl &= ~FFB_DAC_UCTRL_WMODE;
+	uctrl |= FFB_DAC_UCTRL_WM_COMB;
+	uctrl &= ~FFB_DAC_UCTRL_OVENAB;
+	upa_writel(FFB_DAC_UCTRL, &dac->type);
+	upa_writel(uctrl, &dac->value);
+
 	spin_unlock_irqrestore(&par->lock, flags);
 }
 

-- 
René Rebe, ExactCODE GmbH, Berlin, Germany
https://exactco.de • https://t2linux.com • https://patreon.com/renerebe

Re: [PATCH] fbdev/ffb: fix corrupted video output on FFB1

[Helge Deller]

Hello Rene,

On 2/5/26 16:49, René Rebe wrote:
> Fix Sun FFB1 corrupted video out [1] by disabling overlay and
> initializing window mode to a known state. The issue never appeared on
> my FFB2+/vertical nor Elite3D/M6. It could also depend on the PROM
> version.
> 
> /SUNW,ffb@1e,0: FFB at 000001fc00000000, type 11, DAC pnum[236c] rev[10] manuf_rev[4]
> X (II) /dev/fb0: Detected FFB1, Z-buffer, Single-buffered.
> X (II) /dev/fb0: BT9068 (PAC1) ramdac detected (with normal cursor control)
> X (II) /dev/fb0: Detected Creator/Creator3D
> 
> [1] https://www.instagram.com/p/DUTcSmSjSem/

The patch itself seems ok.
But could you please link to a freely accessible website instead of Instagram?
I and many others don't have (and don't want) an instagram account, so
the link is not very useful.

Helge
  
> Signed-off-by: René Rebe <rene@exactco.de>
> Cc: stable@kernel.org
> ---
> Tested on Sun Ultra 2 w/ FFB1 BT9068 (PAC1) ramdac running T2/Linux.
> Defines re-used from xf86-video-sunffb.
> ---
> diff --git a/drivers/video/fbdev/ffb.c b/drivers/video/fbdev/ffb.c
> index 34b6abff9493..8d77f102dd82 100644
> --- a/drivers/video/fbdev/ffb.c
> +++ b/drivers/video/fbdev/ffb.c
> @@ -335,6 +335,9 @@ struct ffb_dac {
>   };
>   
>   #define FFB_DAC_UCTRL		0x1001 /* User Control */
> +#define FFB_DAC_UCTRL_OVENAB	0x00000008 /* Overlay Enable */
> +#define FFB_DAC_UCTRL_WMODE	0x00000030 /* Window Mode */
> +#define FFB_DAC_UCTRL_WM_COMB	0x00000000 /* Window Mode = Combined */
>   #define FFB_DAC_UCTRL_MANREV	0x00000f00 /* 4-bit Manufacturing Revision */
>   #define FFB_DAC_UCTRL_MANREV_SHIFT 8
>   #define FFB_DAC_TGEN		0x6000 /* Timing Generator */
> @@ -425,7 +428,7 @@ static void ffb_switch_from_graph(struct ffb_par *par)
>   {
>   	struct ffb_fbc __iomem *fbc = par->fbc;
>   	struct ffb_dac __iomem *dac = par->dac;
> -	unsigned long flags;
> +	unsigned long flags, uctrl;
>   
>   	spin_lock_irqsave(&par->lock, flags);
>   	FFBWait(par);
> @@ -442,7 +445,7 @@ static void ffb_switch_from_graph(struct ffb_par *par)
>   	upa_writel(par->bg_cache, &fbc->bg);
>   	FFBWait(par);
>   
> -	/* Disable cursor.  */
> +	/* Disable cursor. */
>   	upa_writel(FFB_DAC_CUR_CTRL, &dac->type2);
>   	if (par->flags & FFB_FLAG_INVCURSOR)
>   		upa_writel(0, &dac->value2);
> @@ -450,6 +453,15 @@ static void ffb_switch_from_graph(struct ffb_par *par)
>   		upa_writel((FFB_DAC_CUR_CTRL_P0 |
>   			    FFB_DAC_CUR_CTRL_P1), &dac->value2);
>   
> +	/* Disable overlay and window modes. */
> +	upa_writel(FFB_DAC_UCTRL, &dac->type);
> +	uctrl = upa_readl(&dac->value);
> +	uctrl &= ~FFB_DAC_UCTRL_WMODE;
> +	uctrl |= FFB_DAC_UCTRL_WM_COMB;
> +	uctrl &= ~FFB_DAC_UCTRL_OVENAB;
> +	upa_writel(FFB_DAC_UCTRL, &dac->type);
> +	upa_writel(uctrl, &dac->value);
> +
>   	spin_unlock_irqrestore(&par->lock, flags);
>   }
>   
> 

Re: [PATCH] fbdev/ffb: fix corrupted video output on FFB1

[René Rebe]

Hi,

> On 6. Feb 2026, at 11:12, Helge Deller <deller@gmx.de> wrote:
> 
> Hello Rene,
> 
> On 2/5/26 16:49, René Rebe wrote:
>> Fix Sun FFB1 corrupted video out [1] by disabling overlay and
>> initializing window mode to a known state. The issue never appeared on
>> my FFB2+/vertical nor Elite3D/M6. It could also depend on the PROM
>> version.
>> /SUNW,ffb@1e,0: FFB at 000001fc00000000, type 11, DAC pnum[236c] rev[10] manuf_rev[4]
>> X (II) /dev/fb0: Detected FFB1, Z-buffer, Single-buffered.
>> X (II) /dev/fb0: BT9068 (PAC1) ramdac detected (with normal cursor control)
>> X (II) /dev/fb0: Detected Creator/Creator3D
>> [1] https://www.instagram.com/p/DUTcSmSjSem/
> 
> The patch itself seems ok.
> But could you please link to a freely accessible website instead of Instagram?
> I and many others don't have (and don't want) an instagram account, so
> the link is not very useful.

Well it is more free than accessing Linux Foundation training material ;-)
It was only for illustration purposes if someone wanted to see or follow random
daily  development fun and not that important. Should I resend it w/o it?

Thanks!
	René

> Helge
> 
>> Signed-off-by: René Rebe <rene@exactco.de>
>> Cc: stable@kernel.org
>> ---
>> Tested on Sun Ultra 2 w/ FFB1 BT9068 (PAC1) ramdac running T2/Linux.
>> Defines re-used from xf86-video-sunffb.
>> ---
>> diff --git a/drivers/video/fbdev/ffb.c b/drivers/video/fbdev/ffb.c
>> index 34b6abff9493..8d77f102dd82 100644
>> --- a/drivers/video/fbdev/ffb.c
>> +++ b/drivers/video/fbdev/ffb.c
>> @@ -335,6 +335,9 @@ struct ffb_dac {
>>  };
>>    #define FFB_DAC_UCTRL 0x1001 /* User Control */
>> +#define FFB_DAC_UCTRL_OVENAB 0x00000008 /* Overlay Enable */
>> +#define FFB_DAC_UCTRL_WMODE 0x00000030 /* Window Mode */
>> +#define FFB_DAC_UCTRL_WM_COMB 0x00000000 /* Window Mode = Combined */
>>  #define FFB_DAC_UCTRL_MANREV 0x00000f00 /* 4-bit Manufacturing Revision */
>>  #define FFB_DAC_UCTRL_MANREV_SHIFT 8
>>  #define FFB_DAC_TGEN 0x6000 /* Timing Generator */
>> @@ -425,7 +428,7 @@ static void ffb_switch_from_graph(struct ffb_par *par)
>>  {
>>   struct ffb_fbc __iomem *fbc = par->fbc;
>>   struct ffb_dac __iomem *dac = par->dac;
>> - unsigned long flags;
>> + unsigned long flags, uctrl;
>>     spin_lock_irqsave(&par->lock, flags);
>>   FFBWait(par);
>> @@ -442,7 +445,7 @@ static void ffb_switch_from_graph(struct ffb_par *par)
>>   upa_writel(par->bg_cache, &fbc->bg);
>>   FFBWait(par);
>>  - /* Disable cursor.  */
>> + /* Disable cursor. */
>>   upa_writel(FFB_DAC_CUR_CTRL, &dac->type2);
>>   if (par->flags & FFB_FLAG_INVCURSOR)
>>   upa_writel(0, &dac->value2);
>> @@ -450,6 +453,15 @@ static void ffb_switch_from_graph(struct ffb_par *par)
>>   upa_writel((FFB_DAC_CUR_CTRL_P0 |
>>      FFB_DAC_CUR_CTRL_P1), &dac->value2);
>>  + /* Disable overlay and window modes. */
>> + upa_writel(FFB_DAC_UCTRL, &dac->type);
>> + uctrl = upa_readl(&dac->value);
>> + uctrl &= ~FFB_DAC_UCTRL_WMODE;
>> + uctrl |= FFB_DAC_UCTRL_WM_COMB;
>> + uctrl &= ~FFB_DAC_UCTRL_OVENAB;
>> + upa_writel(FFB_DAC_UCTRL, &dac->type);
>> + upa_writel(uctrl, &dac->value);
>> +
>>   spin_unlock_irqrestore(&par->lock, flags);
>>  }
>>  
> 

-- 
https://exactco.de • https://t2linux.com • https://patreon.com/renerebe

Re: [PATCH] fbdev/ffb: fix corrupted video output on FFB1

[René Rebe]

Hello again,

> On 6. Feb 2026, at 11:30, René Rebe <rene@exactco.de> wrote:
> 
> Hi,
> 
>> On 6. Feb 2026, at 11:12, Helge Deller <deller@gmx.de> wrote:
>> 
>> Hello Rene,
>> 
>> On 2/5/26 16:49, René Rebe wrote:
>>> Fix Sun FFB1 corrupted video out [1] by disabling overlay and
>>> initializing window mode to a known state. The issue never appeared on
>>> my FFB2+/vertical nor Elite3D/M6. It could also depend on the PROM
>>> version.
>>> /SUNW,ffb@1e,0: FFB at 000001fc00000000, type 11, DAC pnum[236c] rev[10] manuf_rev[4]
>>> X (II) /dev/fb0: Detected FFB1, Z-buffer, Single-buffered.
>>> X (II) /dev/fb0: BT9068 (PAC1) ramdac detected (with normal cursor control)
>>> X (II) /dev/fb0: Detected Creator/Creator3D
>>> [1] https://www.instagram.com/p/DUTcSmSjSem/
>> 
>> The patch itself seems ok.
>> But could you please link to a freely accessible website instead of Instagram?
>> I and many others don't have (and don't want) an instagram account, so
>> the link is not very useful.
> 
> Well it is more free than accessing Linux Foundation training material ;-)
> It was only for illustration purposes if someone wanted to see or follow random
> daily  development fun and not that important. Should I resend it w/o it?

While I try to influence next gen to get into OpenSource and low level programming,
how about Mastodon links?

	https://chaos.social/@ReneRebe/116023241660154102

Do you want to edit the patch or should I send a V2?

	René

> Thanks!
> René
> 
>> Helge
>> 
>>> Signed-off-by: René Rebe <rene@exactco.de>
>>> Cc: stable@kernel.org
>>> ---
>>> Tested on Sun Ultra 2 w/ FFB1 BT9068 (PAC1) ramdac running T2/Linux.
>>> Defines re-used from xf86-video-sunffb.
>>> ---
>>> diff --git a/drivers/video/fbdev/ffb.c b/drivers/video/fbdev/ffb.c
>>> index 34b6abff9493..8d77f102dd82 100644
>>> --- a/drivers/video/fbdev/ffb.c
>>> +++ b/drivers/video/fbdev/ffb.c
>>> @@ -335,6 +335,9 @@ struct ffb_dac {
>>> };
>>>   #define FFB_DAC_UCTRL 0x1001 /* User Control */
>>> +#define FFB_DAC_UCTRL_OVENAB 0x00000008 /* Overlay Enable */
>>> +#define FFB_DAC_UCTRL_WMODE 0x00000030 /* Window Mode */
>>> +#define FFB_DAC_UCTRL_WM_COMB 0x00000000 /* Window Mode = Combined */
>>> #define FFB_DAC_UCTRL_MANREV 0x00000f00 /* 4-bit Manufacturing Revision */
>>> #define FFB_DAC_UCTRL_MANREV_SHIFT 8
>>> #define FFB_DAC_TGEN 0x6000 /* Timing Generator */
>>> @@ -425,7 +428,7 @@ static void ffb_switch_from_graph(struct ffb_par *par)
>>> {
>>>  struct ffb_fbc __iomem *fbc = par->fbc;
>>>  struct ffb_dac __iomem *dac = par->dac;
>>> - unsigned long flags;
>>> + unsigned long flags, uctrl;
>>>    spin_lock_irqsave(&par->lock, flags);
>>>  FFBWait(par);
>>> @@ -442,7 +445,7 @@ static void ffb_switch_from_graph(struct ffb_par *par)
>>>  upa_writel(par->bg_cache, &fbc->bg);
>>>  FFBWait(par);
>>> - /* Disable cursor.  */
>>> + /* Disable cursor. */
>>>  upa_writel(FFB_DAC_CUR_CTRL, &dac->type2);
>>>  if (par->flags & FFB_FLAG_INVCURSOR)
>>>  upa_writel(0, &dac->value2);
>>> @@ -450,6 +453,15 @@ static void ffb_switch_from_graph(struct ffb_par *par)
>>>  upa_writel((FFB_DAC_CUR_CTRL_P0 |
>>>     FFB_DAC_CUR_CTRL_P1), &dac->value2);
>>> + /* Disable overlay and window modes. */
>>> + upa_writel(FFB_DAC_UCTRL, &dac->type);
>>> + uctrl = upa_readl(&dac->value);
>>> + uctrl &= ~FFB_DAC_UCTRL_WMODE;
>>> + uctrl |= FFB_DAC_UCTRL_WM_COMB;
>>> + uctrl &= ~FFB_DAC_UCTRL_OVENAB;
>>> + upa_writel(FFB_DAC_UCTRL, &dac->type);
>>> + upa_writel(uctrl, &dac->value);
>>> +
>>>  spin_unlock_irqrestore(&par->lock, flags);
>>> }
>>> 
>> 
> 
> -- 
> https://exactco.de • https://t2linux.com • https://patreon.com/renerebe
> 

-- 
https://exactco.de • https://t2linux.com • https://patreon.com/renerebe

Re: [PATCH] fbdev/ffb: fix corrupted video output on FFB1

[Helge Deller]

On 2/6/26 11:30, René Rebe wrote:
>> On 6. Feb 2026, at 11:12, Helge Deller <deller@gmx.de> wrote:
>>
>> Hello Rene,
>>
>> On 2/5/26 16:49, René Rebe wrote:
>>> Fix Sun FFB1 corrupted video out [1] by disabling overlay and
>>> initializing window mode to a known state. The issue never appeared on
>>> my FFB2+/vertical nor Elite3D/M6. It could also depend on the PROM
>>> version.
>>> /SUNW,ffb@1e,0: FFB at 000001fc00000000, type 11, DAC pnum[236c] rev[10] manuf_rev[4]
>>> X (II) /dev/fb0: Detected FFB1, Z-buffer, Single-buffered.
>>> X (II) /dev/fb0: BT9068 (PAC1) ramdac detected (with normal cursor control)
>>> X (II) /dev/fb0: Detected Creator/Creator3D
>>> [1] https://www.instagram.com/p/DUTcSmSjSem/
>>
>> The patch itself seems ok.
>> But could you please link to a freely accessible website instead of Instagram?
>> I and many others don't have (and don't want) an instagram account, so
>> the link is not very useful.
> 
> Well it is more free than accessing Linux Foundation training material ;-)
> It was only for illustration purposes if someone wanted to see or follow random
> daily  development fun and not that important. Should I resend it w/o it?

No need to resend.
I asked, because I don't know what's visible there, and maybe you
had another link which could have been used instead.
It seems that's not the case, so I'll take the patch as-is.

applied to fbdev git tree.

Thanks!
Helge