Re: [PATCH] memory/samsung: Maybe wrong triming parameter

Krzysztof Kozlowski
2020-05-08T14:46:17Z

On Thu, May 07, 2020 at 04:42:46PM +0100, Lukasz Luba wrote:
> Hi Bernard,
>
>
> On 5/7/20 12:45 PM, Bernard Zhao wrote:
> > In function create_timings_aligned, all the max is to use
> > dmc->min_tck->xxx, aligned with val dmc->timings->xxx.
> > But the dmc->timings->tFAW use dmc->min_tck->tXP?
> > Maybe this point is wrong parameter useing.
> >
> > Signed-off-by: Bernard Zhao <bernard@vivo.com>
> > ---
> > drivers/memory/samsung/exynos5422-dmc.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/memory/samsung/exynos5422-dmc.c b/drivers/memory/samsung/exynos5422-dmc.c
> > index 81a1b1d01683..22a43d662833 100644
> > --- a/drivers/memory/samsung/exynos5422-dmc.c
> > +++ b/drivers/memory/samsung/exynos5422-dmc.c
> > @@ -1091,7 +1091,7 @@ static int create_timings_aligned(struct exynos5_dmc *dmc, u32 *reg_timing_row,
> > /* power related timings */
> > val = dmc->timings->tFAW / clk_period_ps;
> > val += dmc->timings->tFAW % clk_period_ps ? 1 : 0;
> > - val = max(val, dmc->min_tck->tXP);
> > + val = max(val, dmc->min_tck->tFAW);
> > reg = &timing_power[0];
> > *reg_timing_power |= TIMING_VAL2REG(reg, val);
> >
>
> Good catch! Indeed this should be a dmc->min_tck->tFAW used for
> clamping.
>
> It didn't show up in testing because the frequency values based on
> which the 'clk_period_ps' are calculated are sane.
> Check the dump below:
>
> [ 5.458227] DMC: mem tFAW=25000, clk_period_ps=6060
> [ 5.461743] DMC: tFAW=5, tXP=2 val=5
> [ 5.465273] DMC: mem tFAW=25000, clk_period_ps=4854
> [ 5.470101] DMC: tFAW=5, tXP=2 val=6
> [ 5.473668] DMC: mem tFAW=25000, clk_period_ps=3636
> [ 5.478507] DMC: tFAW=5, tXP=2 val=7
> [ 5.482072] DMC: mem tFAW=25000, clk_period_ps=2421
> [ 5.486951] DMC: tFAW=5, tXP=2 val=11
> [ 5.490531] DMC: mem tFAW=25000, clk_period_ps=1841
> [ 5.495439] DMC: tFAW=5, tXP=2 val=14
> [ 5.499113] DMC: mem tFAW=25000, clk_period_ps=1579
> [ 5.503877] DMC: tFAW=5, tXP=2 val=16
> [ 5.507476] DMC: mem tFAW=25000, clk_period_ps=1373
> [ 5.512368] DMC: tFAW=5, tXP=2 val=19
> [ 5.515968] DMC: mem tFAW=25000, clk_period_ps=1212
> [ 5.520826] DMC: tFAW=5, tXP=2 val=21
>
> That's why in the existing configuration it does not harm
> (the calculated 'val' is always >= 5) the board.
>
> But I think this patch should be applied (after small changes in the
> commit message).
>
> @Krzysztof could you have a look on the commit message or take the
> patch with small adjustment in the description, please?
>
> I conditionally give (because of this description):
>
> Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>

Thanks for review.

I applied patch with CC-stable and adjusred commit msg.

Best regards,
Krzysztof