Patchwork [U-Boot,02/10] mx23: Document the tRAS lockout setting in memory initialization

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Submitter Otavio Salvador
Date Jan. 30, 2013, 12:13 p.m.
Message ID <1359548001-14278-3-git-send-email-otavio@ossystems.com.br>
Download mbox | patch
Permalink /patch/216874/
State Changes Requested
Delegated to: Stefano Babic
Headers show

Comments

Otavio Salvador - Jan. 30, 2013, 12:13 p.m.
Add a comment about the tRAS lockout setting of HW_DRAM_CTL08 to
enable the 'Fast Auto Pre-Charge' found in the memory chip. The
setting is applied after memory initialization and it is worth
document it.

Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
---
 arch/arm/cpu/arm926ejs/mxs/spl_mem_init.c | 1 +
 1 file changed, 1 insertion(+)
Marek Vasut - Jan. 30, 2013, 2:10 p.m.
Dear Otavio Salvador,

> Add a comment about the tRAS lockout setting of HW_DRAM_CTL08 to
> enable the 'Fast Auto Pre-Charge' found in the memory chip. The
> setting is applied after memory initialization and it is worth
> document it.
> 
> Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
> ---
>  arch/arm/cpu/arm926ejs/mxs/spl_mem_init.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/arch/arm/cpu/arm926ejs/mxs/spl_mem_init.c
> b/arch/arm/cpu/arm926ejs/mxs/spl_mem_init.c index f8392f6..37b50e9 100644
> --- a/arch/arm/cpu/arm926ejs/mxs/spl_mem_init.c
> +++ b/arch/arm/cpu/arm926ejs/mxs/spl_mem_init.c
> @@ -119,6 +119,7 @@ static void initialize_dram_values(void)
>  		writel(dram_vals[i], MXS_DRAM_BASE + (4 * i));
> 
>  #ifdef CONFIG_MX23
> +	/* Enable tRAS lockout in HW_DRAM_CTL08 */

This does not explain why it must be here and not in the dram_vals table. It 
would be nice to explain it here, since it'd prevent others from sending patch 
stuffing it into the dram_vals table without knowing it must definitelly be 
here.

But why does it have to be here? I wonder ...

>  	writel((1 << 24), MXS_DRAM_BASE + (4 * 8));
>  #endif
>  }

Best regards,
Marek Vasut
Otavio Salvador - Jan. 30, 2013, 3:23 p.m.
On Wed, Jan 30, 2013 at 12:10 PM, Marek Vasut <marex@denx.de> wrote:
> Dear Otavio Salvador,
>
>> Add a comment about the tRAS lockout setting of HW_DRAM_CTL08 to
>> enable the 'Fast Auto Pre-Charge' found in the memory chip. The
>> setting is applied after memory initialization and it is worth
>> document it.
>>
>> Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
>> ---
>>  arch/arm/cpu/arm926ejs/mxs/spl_mem_init.c | 1 +
>>  1 file changed, 1 insertion(+)
>>
>> diff --git a/arch/arm/cpu/arm926ejs/mxs/spl_mem_init.c
>> b/arch/arm/cpu/arm926ejs/mxs/spl_mem_init.c index f8392f6..37b50e9 100644
>> --- a/arch/arm/cpu/arm926ejs/mxs/spl_mem_init.c
>> +++ b/arch/arm/cpu/arm926ejs/mxs/spl_mem_init.c
>> @@ -119,6 +119,7 @@ static void initialize_dram_values(void)
>>               writel(dram_vals[i], MXS_DRAM_BASE + (4 * i));
>>
>>  #ifdef CONFIG_MX23
>> +     /* Enable tRAS lockout in HW_DRAM_CTL08 */
>
> This does not explain why it must be here and not in the dram_vals table. It
> would be nice to explain it here, since it'd prevent others from sending patch
> stuffing it into the dram_vals table without knowing it must definitelly be
> here.

Ok; I will extend the comment.

> But why does it have to be here? I wonder ...

Yes; I don't know as well. We may try to find it out in future but for
now let's keep it as is.

Will change it for v2.

--
Otavio Salvador                             O.S. Systems
E-mail: otavio@ossystems.com.br  http://www.ossystems.com.br
Mobile: +55 53 9981-7854              http://projetos.ossystems.com.br

Patch

diff --git a/arch/arm/cpu/arm926ejs/mxs/spl_mem_init.c b/arch/arm/cpu/arm926ejs/mxs/spl_mem_init.c
index f8392f6..37b50e9 100644
--- a/arch/arm/cpu/arm926ejs/mxs/spl_mem_init.c
+++ b/arch/arm/cpu/arm926ejs/mxs/spl_mem_init.c
@@ -119,6 +119,7 @@  static void initialize_dram_values(void)
 		writel(dram_vals[i], MXS_DRAM_BASE + (4 * i));
 
 #ifdef CONFIG_MX23
+	/* Enable tRAS lockout in HW_DRAM_CTL08 */
 	writel((1 << 24), MXS_DRAM_BASE + (4 * 8));
 #endif
 }