linux-kernel - Re: [PATCH v1 2/4] ARM: tegra: Fix DRAM refresh-interval clobbering on resume from LP1 on Tegra30

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Message-ID: <4f61bf5f-0aa8-df6e-109b-194b08f3374e@nvidia.com>
Date:   Mon, 19 Nov 2018 21:34:06 +0000
From:   Jon Hunter <jonathanh@...dia.com>
To:     Dmitry Osipenko <digetx@...il.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Peter De Schrijver <pdeschrijver@...dia.com>
CC:     <linux-tegra@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1 2/4] ARM: tegra: Fix DRAM refresh-interval clobbering
 on resume from LP1 on Tegra30


On 30/08/2018 19:54, Dmitry Osipenko wrote:
> The DRAM refresh-interval is getting erroneously set to "1" on exiting
> from memory self-refreshing mode. The clobbered interval causes the
> "refresh request overflow timeout" error raised by the External Memory
> Controller on exiting from LP1 on Tegra30.
> 
> Signed-off-by: Dmitry Osipenko <digetx@...il.com>
> ---
>  arch/arm/mach-tegra/sleep-tegra30.S | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/arch/arm/mach-tegra/sleep-tegra30.S b/arch/arm/mach-tegra/sleep-tegra30.S
> index 801fe58978ae..99ac9c6dcf7c 100644
> --- a/arch/arm/mach-tegra/sleep-tegra30.S
> +++ b/arch/arm/mach-tegra/sleep-tegra30.S
> @@ -29,7 +29,6 @@
>  #define EMC_CFG				0xc
>  #define EMC_ADR_CFG			0x10
>  #define EMC_TIMING_CONTROL		0x28
> -#define EMC_REFRESH			0x70
>  #define EMC_NOP				0xdc
>  #define EMC_SELF_REF			0xe0
>  #define EMC_MRW				0xe8
> @@ -459,7 +458,6 @@ emc_wait_auto_cal_onetime:
>  	cmp	r10, #TEGRA30
>  	streq	r1, [r0, #EMC_NOP]
>  	streq	r1, [r0, #EMC_NOP]
> -	streq	r1, [r0, #EMC_REFRESH]
>  
>  	emc_device_mask r1, r0

This does look incorrect and it appears Tegra20 has the same bug.
However, looking at the EMC_REFRESH register it appears that bits 5:0
are the REFRESH_LO and bits 15:6 are the refresh interval. So this seems
to imply the interval is set to 0 and not 1. So maybe the commit message
needs to be fixed up.

The other question I have, should we be restoring the refresh value here
somewhere?

Cheers
Jon

-- 
nvpublic