Thanks,
Vaibhav Hiremath

> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:linux-omap-
> [EMAIL PROTECTED] On Behalf Of Tomi Valkeinen
> Sent: Monday, November 10, 2008 2:01 PM
> To: [EMAIL PROTECTED]
> Cc: [EMAIL PROTECTED]; [EMAIL PROTECTED]; [EMAIL PROTECTED];
> [EMAIL PROTECTED]; [email protected]
> 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) {
> >
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