Fix for dispc's error "omapfb omapfb: irq error status 4020"

Fix for dispc's error "omapfb omapfb: irq error status 4020"

[Rick Bronson]

Folks,

  Please take a look at this change to drivers/video/omap/dispc.c.  It
addresses a problem seen on some boots of OMAP's.  On about 1 in 30
boots one gets an endless stream of interrupts from the
DISPC_IRQ_SYNC_LOST bit in the DISPC_IRQSTATUS register.  The
following messages are printed.

 omapfb omapfb: irq error status 4020

  The correct solution to this problem is to perform a "soft reset"
but that requires a bit of re-architecturing of the code as the init
routine would have to be split up, etc.  See the OMAP pdf, search for
"To clear a synchronization lost interrupt".

  This patch allows the above error message to get printed once and
then disables further DISPC_IRQ_SYNC_LOST interrups.

  Comments?

  Thanks,

 Rick

--- linux-omap-2.6/drivers/video/omap/dispc.c.~1~	2008-11-04 14:23:38.000000000 -0800
+++ linux-omap-2.6/drivers/video/omap/dispc.c	2008-11-07 12:34:54.000000000 -0800
@@ -157,7 +157,7 @@ struct resmap {
 
 #define MAX_IRQ_HANDLERS            4
 
-static struct {
+static struct omapfb_dispc {
 	void __iomem	*base;
 
 	struct omapfb_mem_desc	mem_desc;
@@ -169,6 +169,7 @@ static struct {
 
 	int		ext_mode;
 
+	u32	irq_error_mask;  /* mask used for errors */
 	struct {
 		u32	irq_mask;
 		void	(*callback)(void *);
@@ -812,16 +813,16 @@ static void set_lcd_timings(void)
 	panel->pixel_clock = fck / lck_div / pck_div / 1000;
 }
 
-static void recalc_irq_mask(void)
+static void recalc_irq_mask(struct omapfb_dispc *p_dispc)
 {
 	int i;
-	unsigned long irq_mask = DISPC_IRQ_MASK_ERROR;
+	unsigned long irq_mask = p_dispc->irq_error_mask;
 
 	for (i = 0; i < MAX_IRQ_HANDLERS; i++) {
-		if (!dispc.irq_handlers[i].callback)
+		if (!p_dispc->irq_handlers[i].callback)
 			continue;
 
-		irq_mask |= dispc.irq_handlers[i].irq_mask;
+		irq_mask |= p_dispc->irq_handlers[i].irq_mask;
 	}
 
 	enable_lcd_clocks(1);
@@ -843,7 +844,7 @@ int omap_dispc_request_irq(unsigned long
 		dispc.irq_handlers[i].irq_mask = irq_mask;
 		dispc.irq_handlers[i].callback = callback;
 		dispc.irq_handlers[i].data = data;
-		recalc_irq_mask();
+		recalc_irq_mask(&dispc);
 
 		return 0;
 	}
@@ -863,7 +864,7 @@ void omap_dispc_free_irq(unsigned long i
 			dispc.irq_handlers[i].irq_mask = 0;
 			dispc.irq_handlers[i].callback = NULL;
 			dispc.irq_handlers[i].data = NULL;
-			recalc_irq_mask();
+			recalc_irq_mask(&dispc);
 			return;
 		}
 	}
@@ -884,6 +885,10 @@ static irqreturn_t omap_dispc_irq_handle
 		complete(&dispc.frame_done);
 
 	if (stat & DISPC_IRQ_MASK_ERROR) {
+		if (stat & DISPC_IRQ_SYNC_LOST) {  /* only allow sync lost once or we end up... */
+			dispc.irq_error_mask &= ~DISPC_IRQ_SYNC_LOST;  /* with a barrage of interrupts */
+			recalc_irq_mask(&dispc);
+			}
 		if (printk_ratelimit()) {
 			dev_err(dispc.fbdev->dev, "irq error status %04x\n",
 				stat & 0x7fff);
@@ -897,6 +902,7 @@ static irqreturn_t omap_dispc_irq_handle
 	}
 
 	dispc_write_reg(DISPC_IRQSTATUS, stat);
+	stat = dispc_read_reg(DISPC_IRQSTATUS);
 
 	enable_lcd_clocks(0);
 
@@ -1432,7 +1438,8 @@ static int omap_dispc_init(struct omapfb
 	l = dispc_read_reg(DISPC_IRQSTATUS);
 	dispc_write_reg(DISPC_IRQSTATUS, l);
 
-	recalc_irq_mask();
+	dispc.irq_error_mask = DISPC_IRQ_MASK_ERROR;  /* init error mask */
+	recalc_irq_mask(&dispc);
 
 	if ((r = request_irq(INT_24XX_DSS_IRQ, omap_dispc_irq_handler,
 			   0, MODULE_NAME, fbdev)) < 0) {

Re: Fix for dispc's error "omapfb omapfb: irq error status 4020"

[Koen Kooi]

[-- Attachment #1: Type: text/plain, Size: 3962 bytes --]


Op 7 nov 2008, om 21:55 heeft Rick Bronson het volgende geschreven:

> Folks,
>
>  Please take a look at this change to drivers/video/omap/dispc.c.  It
> addresses a problem seen on some boots of OMAP's.  On about 1 in 30
> boots one gets an endless stream of interrupts from the
> DISPC_IRQ_SYNC_LOST bit in the DISPC_IRQSTATUS register.  The
> following messages are printed.
>
> omapfb omapfb: irq error status 4020
>
>  The correct solution to this problem is to perform a "soft reset"
> but that requires a bit of re-architecturing of the code as the init
> routine would have to be split up, etc.  See the OMAP pdf, search for
> "To clear a synchronization lost interrupt".
>
>  This patch allows the above error message to get printed once and
> then disables further DISPC_IRQ_SYNC_LOST interrups.
>
>  Comments?

I can trigger this with all boots using Tomi's DSS patches on a rev C  
prototype beagle (ES3.0 3530), so those probably need a similar patch :)

regards,

Koen


>
>
>  Thanks,
>
> Rick
>
> --- linux-omap-2.6/drivers/video/omap/dispc.c.~1~	2008-11-04  
> 14:23:38.000000000 -0800
> +++ linux-omap-2.6/drivers/video/omap/dispc.c	2008-11-07  
> 12:34:54.000000000 -0800
> @@ -157,7 +157,7 @@ struct resmap {
>
> #define MAX_IRQ_HANDLERS            4
>
> -static struct {
> +static struct omapfb_dispc {
> 	void __iomem	*base;
>
> 	struct omapfb_mem_desc	mem_desc;
> @@ -169,6 +169,7 @@ static struct {
>
> 	int		ext_mode;
>
> +	u32	irq_error_mask;  /* mask used for errors */
> 	struct {
> 		u32	irq_mask;
> 		void	(*callback)(void *);
> @@ -812,16 +813,16 @@ static void set_lcd_timings(void)
> 	panel->pixel_clock = fck / lck_div / pck_div / 1000;
> }
>
> -static void recalc_irq_mask(void)
> +static void recalc_irq_mask(struct omapfb_dispc *p_dispc)
> {
> 	int i;
> -	unsigned long irq_mask = DISPC_IRQ_MASK_ERROR;
> +	unsigned long irq_mask = p_dispc->irq_error_mask;
>
> 	for (i = 0; i < MAX_IRQ_HANDLERS; i++) {
> -		if (!dispc.irq_handlers[i].callback)
> +		if (!p_dispc->irq_handlers[i].callback)
> 			continue;
>
> -		irq_mask |= dispc.irq_handlers[i].irq_mask;
> +		irq_mask |= p_dispc->irq_handlers[i].irq_mask;
> 	}
>
> 	enable_lcd_clocks(1);
> @@ -843,7 +844,7 @@ int omap_dispc_request_irq(unsigned long
> 		dispc.irq_handlers[i].irq_mask = irq_mask;
> 		dispc.irq_handlers[i].callback = callback;
> 		dispc.irq_handlers[i].data = data;
> -		recalc_irq_mask();
> +		recalc_irq_mask(&dispc);
>
> 		return 0;
> 	}
> @@ -863,7 +864,7 @@ void omap_dispc_free_irq(unsigned long i
> 			dispc.irq_handlers[i].irq_mask = 0;
> 			dispc.irq_handlers[i].callback = NULL;
> 			dispc.irq_handlers[i].data = NULL;
> -			recalc_irq_mask();
> +			recalc_irq_mask(&dispc);
> 			return;
> 		}
> 	}
> @@ -884,6 +885,10 @@ static irqreturn_t omap_dispc_irq_handle
> 		complete(&dispc.frame_done);
>
> 	if (stat & DISPC_IRQ_MASK_ERROR) {
> +		if (stat & DISPC_IRQ_SYNC_LOST) {  /* only allow sync lost once  
> or we end up... */
> +			dispc.irq_error_mask &= ~DISPC_IRQ_SYNC_LOST;  /* with a barrage  
> of interrupts */
> +			recalc_irq_mask(&dispc);
> +			}
> 		if (printk_ratelimit()) {
> 			dev_err(dispc.fbdev->dev, "irq error status %04x\n",
> 				stat & 0x7fff);
> @@ -897,6 +902,7 @@ static irqreturn_t omap_dispc_irq_handle
> 	}
>
> 	dispc_write_reg(DISPC_IRQSTATUS, stat);
> +	stat = dispc_read_reg(DISPC_IRQSTATUS);
>
> 	enable_lcd_clocks(0);
>
> @@ -1432,7 +1438,8 @@ static int omap_dispc_init(struct omapfb
> 	l = dispc_read_reg(DISPC_IRQSTATUS);
> 	dispc_write_reg(DISPC_IRQSTATUS, l);
>
> -	recalc_irq_mask();
> +	dispc.irq_error_mask = DISPC_IRQ_MASK_ERROR;  /* init error mask */
> +	recalc_irq_mask(&dispc);
>
> 	if ((r = request_irq(INT_24XX_DSS_IRQ, omap_dispc_irq_handler,
> 			   0, MODULE_NAME, fbdev)) < 0) {
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux- 
> omap" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>


[-- Attachment #2: This is a digitally signed message part --]
[-- Type: application/pgp-signature, Size: 186 bytes --]

Re: Fix for dispc's error "omapfb omapfb: irq error status 4020"

[Tomi Valkeinen]

Hi,

On Fri, 2008-11-07 at 12:55 -0800, ext Rick Bronson wrote:
> Folks,
> 
>   Please take a look at this change to drivers/video/omap/dispc.c.  It
> addresses a problem seen on some boots of OMAP's.  On about 1 in 30
> boots one gets an endless stream of interrupts from the
> DISPC_IRQ_SYNC_LOST bit in the DISPC_IRQSTATUS register.  The
> following messages are printed.
> 
>  omapfb omapfb: irq error status 4020
> 
>   The correct solution to this problem is to perform a "soft reset"
> but that requires a bit of re-architecturing of the code as the init
> routine would have to be split up, etc.  See the OMAP pdf, search for
> "To clear a synchronization lost interrupt".
> 
>   This patch allows the above error message to get printed once and
> then disables further DISPC_IRQ_SYNC_LOST interrups.
> 
>   Comments?

I think the correct solution would be to find out why we get sync lost
errors and fix that. Your patch just hides the problem. 

However, I agree that it's not good to just keep spamming the error,
possibly making the board freeze. The new DSS turns the display off
after 100 error messages. But I don't think just hiding the interrupt is
a good change.

> 
>   Thanks,
> 
>  Rick

Tomi


> 
> --- linux-omap-2.6/drivers/video/omap/dispc.c.~1~	2008-11-04 14:23:38.000000000 -0800
> +++ linux-omap-2.6/drivers/video/omap/dispc.c	2008-11-07 12:34:54.000000000 -0800
> @@ -157,7 +157,7 @@ struct resmap {
>  
>  #define MAX_IRQ_HANDLERS            4
>  
> -static struct {
> +static struct omapfb_dispc {
>  	void __iomem	*base;
>  
>  	struct omapfb_mem_desc	mem_desc;
> @@ -169,6 +169,7 @@ static struct {
>  
>  	int		ext_mode;
>  
> +	u32	irq_error_mask;  /* mask used for errors */
>  	struct {
>  		u32	irq_mask;
>  		void	(*callback)(void *);
> @@ -812,16 +813,16 @@ static void set_lcd_timings(void)
>  	panel->pixel_clock = fck / lck_div / pck_div / 1000;
>  }
>  
> -static void recalc_irq_mask(void)
> +static void recalc_irq_mask(struct omapfb_dispc *p_dispc)
>  {
>  	int i;
> -	unsigned long irq_mask = DISPC_IRQ_MASK_ERROR;
> +	unsigned long irq_mask = p_dispc->irq_error_mask;
>  
>  	for (i = 0; i < MAX_IRQ_HANDLERS; i++) {
> -		if (!dispc.irq_handlers[i].callback)
> +		if (!p_dispc->irq_handlers[i].callback)
>  			continue;
>  
> -		irq_mask |= dispc.irq_handlers[i].irq_mask;
> +		irq_mask |= p_dispc->irq_handlers[i].irq_mask;
>  	}
>  
>  	enable_lcd_clocks(1);
> @@ -843,7 +844,7 @@ int omap_dispc_request_irq(unsigned long
>  		dispc.irq_handlers[i].irq_mask = irq_mask;
>  		dispc.irq_handlers[i].callback = callback;
>  		dispc.irq_handlers[i].data = data;
> -		recalc_irq_mask();
> +		recalc_irq_mask(&dispc);
>  
>  		return 0;
>  	}
> @@ -863,7 +864,7 @@ void omap_dispc_free_irq(unsigned long i
>  			dispc.irq_handlers[i].irq_mask = 0;
>  			dispc.irq_handlers[i].callback = NULL;
>  			dispc.irq_handlers[i].data = NULL;
> -			recalc_irq_mask();
> +			recalc_irq_mask(&dispc);
>  			return;
>  		}
>  	}
> @@ -884,6 +885,10 @@ static irqreturn_t omap_dispc_irq_handle
>  		complete(&dispc.frame_done);
>  
>  	if (stat & DISPC_IRQ_MASK_ERROR) {
> +		if (stat & DISPC_IRQ_SYNC_LOST) {  /* only allow sync lost once or we end up... */
> +			dispc.irq_error_mask &= ~DISPC_IRQ_SYNC_LOST;  /* with a barrage of interrupts */
> +			recalc_irq_mask(&dispc);
> +			}
>  		if (printk_ratelimit()) {
>  			dev_err(dispc.fbdev->dev, "irq error status %04x\n",
>  				stat & 0x7fff);
> @@ -897,6 +902,7 @@ static irqreturn_t omap_dispc_irq_handle
>  	}
>  
>  	dispc_write_reg(DISPC_IRQSTATUS, stat);
> +	stat = dispc_read_reg(DISPC_IRQSTATUS);
>  
>  	enable_lcd_clocks(0);
>  
> @@ -1432,7 +1438,8 @@ static int omap_dispc_init(struct omapfb
>  	l = dispc_read_reg(DISPC_IRQSTATUS);
>  	dispc_write_reg(DISPC_IRQSTATUS, l);
>  
> -	recalc_irq_mask();
> +	dispc.irq_error_mask = DISPC_IRQ_MASK_ERROR;  /* init error mask */
> +	recalc_irq_mask(&dispc);
>  
>  	if ((r = request_irq(INT_24XX_DSS_IRQ, omap_dispc_irq_handler,
>  			   0, MODULE_NAME, fbdev)) < 0) {
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-omap" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

RE: Fix for dispc's error "omapfb omapfb: irq error status 4020"

[Hiremath, Vaibhav]

Thanks,
Vaibhav Hiremath

> -----Original Message-----
> From: linux-omap-owner@vger.kernel.org [mailto:linux-omap-
> owner@vger.kernel.org] On Behalf Of Tomi Valkeinen
> Sent: Monday, November 10, 2008 2:01 PM
> To: rick@efn.org
> Cc: imre.deak@nokia.com; aam@ridgerun.com; juha.yrjola@nokia.com;
> dirk.behme@de.bosch.com; linux-omap@vger.kernel.org
> Subject: Re: Fix for dispc's error "omapfb omapfb: irq error status
> 4020"
> 
> Hi,
> 
> On Fri, 2008-11-07 at 12:55 -0800, ext Rick Bronson wrote:
> > Folks,
> >
> >   Please take a look at this change to drivers/video/omap/dispc.c.
> It
> > addresses a problem seen on some boots of OMAP's.  On about 1 in
> 30
> > boots one gets an endless stream of interrupts from the
> > DISPC_IRQ_SYNC_LOST bit in the DISPC_IRQSTATUS register.  The
> > following messages are printed.
> >
> >  omapfb omapfb: irq error status 4020
> >
> >   The correct solution to this problem is to perform a "soft
> reset"
> > but that requires a bit of re-architecturing of the code as the
> init
> > routine would have to be split up, etc.  See the OMAP pdf, search
> for
> > "To clear a synchronization lost interrupt".
> >
> >   This patch allows the above error message to get printed once
> and
> > then disables further DISPC_IRQ_SYNC_LOST interrups.
> >
> >   Comments?
> 
> I think the correct solution would be to find out why we get sync
> lost
> errors and fix that. Your patch just hides the problem.
> 
> However, I agree that it's not good to just keep spamming the error,
> possibly making the board freeze. The new DSS turns the display off
> after 100 error messages. But I don't think just hiding the
> interrupt is
> a good change.
> 
[Hiremath, Vaibhav] Yes, it is not a good practice to hide any interrupts. But I think even instead of turning of the DSS, you should reset the DSS and reconfigure it with default values or preserve the state before resetting and configure it again.
I agree to the point that, it requires lot of re-architectureing to the current driver. But I believe it should be possible with new omap2 version.

> >
> >   Thanks,
> >
> >  Rick
> 
> Tomi
> 
> 
> >
> > --- linux-omap-2.6/drivers/video/omap/dispc.c.~1~	2008-11-04
> 14:23:38.000000000 -0800
> > +++ linux-omap-2.6/drivers/video/omap/dispc.c	2008-11-07
> 12:34:54.000000000 -0800
> > @@ -157,7 +157,7 @@ struct resmap {
> >
> >  #define MAX_IRQ_HANDLERS            4
> >
> > -static struct {
> > +static struct omapfb_dispc {
> >  	void __iomem	*base;
> >
> >  	struct omapfb_mem_desc	mem_desc;
> > @@ -169,6 +169,7 @@ static struct {
> >
> >  	int		ext_mode;
> >
> > +	u32	irq_error_mask;  /* mask used for errors */
> >  	struct {
> >  		u32	irq_mask;
> >  		void	(*callback)(void *);
> > @@ -812,16 +813,16 @@ static void set_lcd_timings(void)
> >  	panel->pixel_clock = fck / lck_div / pck_div / 1000;
> >  }
> >
> > -static void recalc_irq_mask(void)
> > +static void recalc_irq_mask(struct omapfb_dispc *p_dispc)
> >  {
> >  	int i;
> > -	unsigned long irq_mask = DISPC_IRQ_MASK_ERROR;
> > +	unsigned long irq_mask = p_dispc->irq_error_mask;
> >
> >  	for (i = 0; i < MAX_IRQ_HANDLERS; i++) {
> > -		if (!dispc.irq_handlers[i].callback)
> > +		if (!p_dispc->irq_handlers[i].callback)
> >  			continue;
> >
> > -		irq_mask |= dispc.irq_handlers[i].irq_mask;
> > +		irq_mask |= p_dispc->irq_handlers[i].irq_mask;
> >  	}
> >
> >  	enable_lcd_clocks(1);
> > @@ -843,7 +844,7 @@ int omap_dispc_request_irq(unsigned long
> >  		dispc.irq_handlers[i].irq_mask = irq_mask;
> >  		dispc.irq_handlers[i].callback = callback;
> >  		dispc.irq_handlers[i].data = data;
> > -		recalc_irq_mask();
> > +		recalc_irq_mask(&dispc);
> >
> >  		return 0;
> >  	}
> > @@ -863,7 +864,7 @@ void omap_dispc_free_irq(unsigned long i
> >  			dispc.irq_handlers[i].irq_mask = 0;
> >  			dispc.irq_handlers[i].callback = NULL;
> >  			dispc.irq_handlers[i].data = NULL;
> > -			recalc_irq_mask();
> > +			recalc_irq_mask(&dispc);
> >  			return;
> >  		}
> >  	}
> > @@ -884,6 +885,10 @@ static irqreturn_t omap_dispc_irq_handle
> >  		complete(&dispc.frame_done);
> >
> >  	if (stat & DISPC_IRQ_MASK_ERROR) {
> > +		if (stat & DISPC_IRQ_SYNC_LOST) {  /* only allow sync
> lost once or we end up... */
> > +			dispc.irq_error_mask &= ~DISPC_IRQ_SYNC_LOST;  /*
> with a barrage of interrupts */
> > +			recalc_irq_mask(&dispc);
> > +			}
> >  		if (printk_ratelimit()) {
> >  			dev_err(dispc.fbdev->dev, "irq error status
> %04x\n",
> >  				stat & 0x7fff);
> > @@ -897,6 +902,7 @@ static irqreturn_t omap_dispc_irq_handle
> >  	}
> >
> >  	dispc_write_reg(DISPC_IRQSTATUS, stat);
> > +	stat = dispc_read_reg(DISPC_IRQSTATUS);
> >
> >  	enable_lcd_clocks(0);
> >
> > @@ -1432,7 +1438,8 @@ static int omap_dispc_init(struct omapfb
> >  	l = dispc_read_reg(DISPC_IRQSTATUS);
> >  	dispc_write_reg(DISPC_IRQSTATUS, l);
> >
> > -	recalc_irq_mask();
> > +	dispc.irq_error_mask = DISPC_IRQ_MASK_ERROR;  /* init error
> mask */
> > +	recalc_irq_mask(&dispc);
> >
> >  	if ((r = request_irq(INT_24XX_DSS_IRQ, omap_dispc_irq_handler,
> >  			   0, MODULE_NAME, fbdev)) < 0) {
> >
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-
> omap" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-
> omap" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: Fix for dispc's error "omapfb omapfb: irq error status 4020"

[Tomi Valkeinen]

Hi,

On Fri, 2008-11-07 at 12:55 -0800, ext Rick Bronson wrote:
> Folks,
> 
>   Please take a look at this change to drivers/video/omap/dispc.c.  It
> addresses a problem seen on some boots of OMAP's.  On about 1 in 30
> boots one gets an endless stream of interrupts from the
> DISPC_IRQ_SYNC_LOST bit in the DISPC_IRQSTATUS register.  The
> following messages are printed.
> 
>  omapfb omapfb: irq error status 4020

Can you try the patch below if it fixes this problem for you? On my new
display subsystem adding a sleep between enabling clocks and doing the
soft reset removed the problem.

I tried a bit with different sleep times. With 1ms sleep I still got
sync losts. With 10ms I didn't, but I went safe and put 40ms.

 Tomi



diff --git a/drivers/video/omap/dispc.c b/drivers/video/omap/dispc.c
index c140c21..bdfda0c 100644
--- a/drivers/video/omap/dispc.c
+++ b/drivers/video/omap/dispc.c
@@ -24,6 +24,7 @@
 #include <linux/vmalloc.h>
 #include <linux/clk.h>
 #include <linux/io.h>
+#include <linux/delay.h>
 
 #include <mach/sram.h>
 #include <mach/omapfb.h>
@@ -1402,6 +1403,10 @@ static int omap_dispc_init(struct omapfb_device *fbdev, int ext_mode,
                /* Reset monitoring works only w/ the 54M clk */
                enable_digit_clocks(1);
 
+               /* We need to wait here a bit, otherwise we sometimes start to get
+                * synclost errors. */
+               msleep(40);
+
                /* Soft reset */
                MOD_REG_FLD(DISPC_SYSCONFIG, 1 << 1, 1 << 1);

Re: Fix for dispc's error "omapfb omapfb: irq error status 4020"

[Tony Lindgren]

* Tomi Valkeinen <tomi.valkeinen@nokia.com> [081113 06:06]:
> Hi,
> 
> On Fri, 2008-11-07 at 12:55 -0800, ext Rick Bronson wrote:
> > Folks,
> > 
> >   Please take a look at this change to drivers/video/omap/dispc.c.  It
> > addresses a problem seen on some boots of OMAP's.  On about 1 in 30
> > boots one gets an endless stream of interrupts from the
> > DISPC_IRQ_SYNC_LOST bit in the DISPC_IRQSTATUS register.  The
> > following messages are printed.
> > 
> >  omapfb omapfb: irq error status 4020
> 
> Can you try the patch below if it fixes this problem for you? On my new
> display subsystem adding a sleep between enabling clocks and doing the
> soft reset removed the problem.
> 
> I tried a bit with different sleep times. With 1ms sleep I still got
> sync losts. With 10ms I didn't, but I went safe and put 40ms.

Here's my canned fbdev reply for this tread too:

Guys, please take this discussion to fbdev mailing list and cc
linux-omap list. I'm not going to push any more omap fbdev patches,
so please send the patches against mainline kernel to fbdev list.

Regards,

Tony

> 
>  Tomi
> 
> 
> 
> diff --git a/drivers/video/omap/dispc.c b/drivers/video/omap/dispc.c
> index c140c21..bdfda0c 100644
> --- a/drivers/video/omap/dispc.c
> +++ b/drivers/video/omap/dispc.c
> @@ -24,6 +24,7 @@
>  #include <linux/vmalloc.h>
>  #include <linux/clk.h>
>  #include <linux/io.h>
> +#include <linux/delay.h>
>  
>  #include <mach/sram.h>
>  #include <mach/omapfb.h>
> @@ -1402,6 +1403,10 @@ static int omap_dispc_init(struct omapfb_device *fbdev, int ext_mode,
>                 /* Reset monitoring works only w/ the 54M clk */
>                 enable_digit_clocks(1);
>  
> +               /* We need to wait here a bit, otherwise we sometimes start to get
> +                * synclost errors. */
> +               msleep(40);
> +
>                 /* Soft reset */
>                 MOD_REG_FLD(DISPC_SYSCONFIG, 1 << 1, 1 << 1);
> 
> 
> --
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> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: Fix for dispc's error "omapfb omapfb: irq error status 4020"

[Grazvydas Ignotas]

[-- Attachment #1: Type: text/plain, Size: 1412 bytes --]

On Thu, Nov 13, 2008 at 4:06 PM, Tomi Valkeinen
<tomi.valkeinen@nokia.com> wrote:
> Hi,
>
> On Fri, 2008-11-07 at 12:55 -0800, ext Rick Bronson wrote:
>> Folks,
>>
>>   Please take a look at this change to drivers/video/omap/dispc.c.  It
>> addresses a problem seen on some boots of OMAP's.  On about 1 in 30
>> boots one gets an endless stream of interrupts from the
>> DISPC_IRQ_SYNC_LOST bit in the DISPC_IRQSTATUS register.  The
>> following messages are printed.
>>
>>  omapfb omapfb: irq error status 4020
>
> Can you try the patch below if it fixes this problem for you? On my new
> display subsystem adding a sleep between enabling clocks and doing the
> soft reset removed the problem.
>
> I tried a bit with different sleep times. With 1ms sleep I still got
> sync losts. With 10ms I didn't, but I went safe and put 40ms.

Unfortunately sleeping there doesn't help for pandora. I've tried
10ms, 40ms, 400ms (this seems to be used by DSS2 now).

However because we are also setting up the display in u-boot for
pandora, I can hook up irq handler early and wait for frame done irq
before resetting DSS (patch attached). With this I've done ~50 reboots
now and hadn't got any sync lost interrupts yet.

In case display is not enabled in bootloader waiting for interrupt
just times out there, so no harm made. This probably could substitute
that sleep, so maybe this solution could be considered for DSS2.

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #2: dispc.patch --]
[-- Type: text/x-diff; name=dispc.patch, Size: 1872 bytes --]

diff --git a/drivers/video/omap/dispc.c b/drivers/video/omap/dispc.c
index c140c21..e73d04a 100644
--- a/drivers/video/omap/dispc.c
+++ b/drivers/video/omap/dispc.c
@@ -1398,10 +1398,31 @@ static int omap_dispc_init(struct omapfb_device *fbdev, int ext_mode,
 	}
 #endif
 
+	l = dispc_read_reg(DISPC_IRQSTATUS);
+	dispc_write_reg(DISPC_IRQSTATUS, l);
+
+	recalc_irq_mask();
+
+	if ((r = request_irq(INT_24XX_DSS_IRQ, omap_dispc_irq_handler,
+			   0, MODULE_NAME, fbdev)) < 0) {
+		dev_err(dispc.fbdev->dev, "can't get DSS IRQ\n");
+		goto fail1;
+	}
+
 	if (!skip_init) {
 		/* Reset monitoring works only w/ the 54M clk */
 		enable_digit_clocks(1);
 
+		/* We have to wait here to avoid occasional SYNC LOST errors */
+		MOD_REG_FLD(DISPC_IRQENABLE, 1, 1);
+		omap_dispc_enable_lcd_out(0);	/* if bootloader enabled it */
+		if (!wait_for_completion_timeout(&dispc.frame_done,
+				msecs_to_jiffies(400))) {
+			dev_err(dispc.fbdev->dev,
+				"timeout waiting for FRAME DONE\n");
+		}
+		MOD_REG_FLD(DISPC_IRQENABLE, 1, 0);
+
 		/* Soft reset */
 		MOD_REG_FLD(DISPC_SYSCONFIG, 1 << 1, 1 << 1);
 
@@ -1410,7 +1431,7 @@ static int omap_dispc_init(struct omapfb_device *fbdev, int ext_mode,
 				dev_err(dispc.fbdev->dev, "soft reset failed\n");
 				r = -ENODEV;
 				enable_digit_clocks(0);
-				goto fail1;
+				goto fail2;
 			}
 		}
 
@@ -1429,16 +1450,6 @@ static int omap_dispc_init(struct omapfb_device *fbdev, int ext_mode,
 	l |= 1 << 9;
 	dispc_write_reg(DISPC_CONFIG, l);
 
-	l = dispc_read_reg(DISPC_IRQSTATUS);
-	dispc_write_reg(DISPC_IRQSTATUS, l);
-
-	recalc_irq_mask();
-
-	if ((r = request_irq(INT_24XX_DSS_IRQ, omap_dispc_irq_handler,
-			   0, MODULE_NAME, fbdev)) < 0) {
-		dev_err(dispc.fbdev->dev, "can't get DSS IRQ\n");
-		goto fail1;
-	}
 
 	/* L3 firewall setting: enable access to OCM RAM */
 	__raw_writel(0x402000b0, IO_ADDRESS(0x680050a0));

Re: Fix for dispc's error "omapfb omapfb: irq error status 4020"

[Rick Bronson]

Tomi,

  I agree with both of you.  My patch is a bandaid at best.  I spend a
fair amount of time trying to find out what's causing the sync lost
interrupts in the first place, mostly be doing peripheral memory space
comparisons of good/bad boots.  This let to nothing, all of the
registers off the DSS were the same except for the interrupt pending.

  This led me to implementing the "soft reset" mentioned in the OMAP3
pdf.  But this would be a big change and I'm not too familiar with
that code.  Plus I didn't even have a DVI display until yesterday...

  Rick

> I think the correct solution would be to find out why we get sync lost
> errors and fix that. Your patch just hides the problem. 
> 
> However, I agree that it's not good to just keep spamming the error,
> possibly making the board freeze. The new DSS turns the display off
> after 100 error messages. But I don't think just hiding the interrupt
> is a good change.
> 
> [Hiremath, Vaibhav] Yes, it is not a good practice to hide any
> interrupts. But I think even instead of turning of the DSS, you should
> reset the DSS and reconfigure it with default values or preserve the
> state before resetting and configure it again.  I agree to the point
> that, it requires lot of re-architectureing to the current driver. But
> I believe it should be possible with new omap2 version.
>