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

[Venkatraman S <svenkatr@ti.com>]

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.
Thanks,

Venkat.
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