Re: [PATCH v2] dma: fix scope of errata i88 upto 3430ES1.0

[Tony Lindgren <tony@atomide.com>]

* Venkatraman S <svenkatr@ti.com> [100426 07:46]:
> Tony Lindgren <tony@atomide.com> wrote:
> > * Venkatraman S <svenkatr@ti.com> [100419 03:47]:
> >> Hi Tony,
> >> > Venkatraman S <svenkatr@ti.com> wrote:
> >> > From 2799506180649cbb61d24cf2b4171425b2e1fa80 Mon Sep 17 00:00:00 2001
> >> > From: Venkatraman S <svenkatr@ti.com>
> >> > Date: Mon, 5 Apr 2010 20:56:27 +0530
> >> > Subject: [PATCH] dma: fix scope of errata i88 upto 3430ES1.0
> >> >
> >> > DMA errata for special end of block programming is applicable
> >> > only for OMAP2430 & OMAP3430 ES1.0.
> >> > This patch does the necessary checks before the workaround
> >> > is applied. Tested on 3430 SDP
> >> >
> >> > Signed-off-by: Thara Gopinath <thara@ti.com>
> >> > Signed-off-by: Venkatraman S <svenkatr@ti.com>
> >> > Reviewed-by: Shilimkar Santosh <santosh.shilimkar@ti.com>
> >> > ---
> >> > From v1, removed the redundant omap3430() check
> >> >
> >> >  arch/arm/plat-omap/dma.c |   20 ++++++++++++--------
> >> >  1 files changed, 12 insertions(+), 8 deletions(-)
> >> >
> >> > diff --git a/arch/arm/plat-omap/dma.c b/arch/arm/plat-omap/dma.c
> >> > index 2ab224c..a9b480a 100644
> >> > --- a/arch/arm/plat-omap/dma.c
> >> > +++ b/arch/arm/plat-omap/dma.c
> >> > @@ -1663,14 +1663,17 @@ int omap_stop_dma_chain_transfers(int chain_id)
> >> >        channels = dma_linked_lch[chain_id].linked_dmach_q;
> >> >
> >> >        /*
> >> > -        * DMA Errata:
> >> > -        * Special programming model needed to disable DMA before end of block
> >> > +        * DMA Errata: i88
> >> > +        * Special programming model needed
> >> > +        * to disable DMA before end of block
> >> >         */
> >> >        sys_cf = dma_read(OCP_SYSCONFIG);
> >> > -       l = sys_cf;
> >> > -       /* Middle mode reg set no Standby */
> >> > -       l &= ~((1 << 12)|(1 << 13));
> >> > -       dma_write(l, OCP_SYSCONFIG);
> >> > +       if (cpu_is_omap2430() || (omap_rev() == OMAP3430_REV_ES1_0)) {
> >> > +               l = sys_cf;
> >> > +               /* Middle mode reg set no Standby */
> >> > +               l &= ~((1 << 12)|(1 << 13));
> >> > +               dma_write(l, OCP_SYSCONFIG);
> >> > +       }
> >> >
> >> >        for (i = 0; i < dma_linked_lch[chain_id].no_of_lchs_linked; i++) {
> >> >
> >
> > What about other omaps? It seems that we're currently doing the workaround
> > for all omaps. Seems like "Tested on 3430 SDP" is not quite safe enough
> > for making change that might affect other omaps.
> >
> > Tony
> 
>      The Errata document specifically mentions that the workaround is
> needed only for
> 3430 ES1.0 or earlier. I had actually tested on the ES2.0. [Now that
> you have mentioned it,
> I tested on 3630 and 4430 as well]
> Let me know if you need more test results or information.

Uhh. The old code does this for all omaps. I rather trust the existing
than TI documentation. What about 2420 and 2430?

Regards,

Tony
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