From: Sascha Hauer <s.hauer@pengutronix.de>
To: Giorgio Dal Molin <giorgio.nicole@arcor.de>
Cc: barebox@lists.infradead.org
Subject: Re: problems with am335x_sdram_size()
Date: Fri, 2 Mar 2018 08:26:06 +0100 [thread overview]
Message-ID: <20180302072606.nn5o4mj7zbe4pyna@pengutronix.de> (raw)
In-Reply-To: <377910125.70611.1519914213534@mail.vodafone.de>
On Thu, Mar 01, 2018 at 03:23:33PM +0100, Giorgio Dal Molin wrote:
> Hi,
>
> working with the TI AM335x Evaluation Module I noticed that the function
> am335x_sdram_size() always returns 0 instead of the computed sdram size.
>
> I could trace back the problem to the fact that the function does its
> computation based on the value of the register CM_EMIF_SDRAM_CONFIG
> (addr. 0x44e10110), but this register is not written to by the function
> am33xx_config_sdram() and just returns its initial value (0).
> The datasheet says CM_EMIF_SDRAM_CONFIG should have the same value as
> AM33XX_EMIF4_0_REG(SDRAM_CONFIG) (addr. 0x4c000008)
CM_EMIF_SDRAM_CONFIG is written when regs->zq_config is set and if it's
set then indeed the same value is written there as also written to
AM33XX_EMIF4_0_REG(SDRAM_CONFIG).
>
> To conclude, to fix the problem with am335x_sdram_size() you can either
> use AM33XX_EMIF4_0_REG(SDRAM_CONFIG) instead of CM_EMIF_SDRAM_CONFIG
> in am335x_sdram_size().
>
> or
>
> initialize CM_EMIF_SDRAM_CONFIG in am33xx_config_sdram() with the same value
> as AM33XX_EMIF4_0_REG(SDRAM_CONFIG) (regs->sdram_config)
I'm fine with either way. Maybe the datasheet gives us a hint which way
to choose? Why is CM_EMIF_SDRAM_CONFIG only written when regs->zq_config
is set? Is this correct?
Sascha
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next prev parent reply other threads:[~2018-03-02 7:26 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-01 14:23 Giorgio Dal Molin
2018-03-02 7:26 ` Sascha Hauer [this message]
2018-03-02 14:11 ` Giorgio Dal Molin
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