Re: [PATCH master 3/4] ddr: imx8m: workaround old spreadsheets not initializing ADDRMAP7

[Teresa Remmet <T.Remmet@phytec.de>]

Hello Ahmad,

Am Donnerstag, dem 23.06.2022 um 12:30 +0200 schrieb Ahmad Fatoum:
> Older NXP DDR spreadsheets don't initialize ADDRMAP7, leaving it at
> its
> POR default of zero. Now that barebox looks at ADDRMAP7 to be able to
> correctly detect bigger memory sizes, barebox proper on out-of-tree
> boards with older spreadsheets may read back 4x times as much RAM
> as actually fitted.
> 
> Work around this by writing a trailing 0xf0f (the neutral ignore-me
> value for the register) if the register wasn't written through
> dram_timing_info::ddrc_cfg. We consider this safe to do, because
> the DDRC is held in reset while these values are programmed.

have you tried this patch without actually updating the RAM Timings (
so patch 2/4)?
I have just played around also setting ADDRMAP7 right before 
ddr_cfg_umctl2() without fixing the timings and the register was 0
again after startup and so the RAM size wrong.
So it seems to me that the value is overwritten/resetted at some other
point again ... or maybe I just did something wrong.

Regards,
Teresa

> 
> Fixes: dad2b5636bd8 ("ARM: imx: Add imx8 support for 18 bit SDRAM row
> size handle")
> Fixes: 6cf197fa61f9 ("arm: imx: mmdc_size: Increase row_max for
> imx8m")
> Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
> ---
>  drivers/ddr/imx8m/ddr_init.c | 18 ++++++++++++++++++
>  drivers/ddr/imx8m/helper.c   |  6 ++++++
>  include/soc/imx8m/ddr.h      |  1 +
>  3 files changed, 25 insertions(+)
> 
> diff --git a/drivers/ddr/imx8m/ddr_init.c
> b/drivers/ddr/imx8m/ddr_init.c
> index ae05b136229c..9a4b4e2ca88a 100644
> --- a/drivers/ddr/imx8m/ddr_init.c
> +++ b/drivers/ddr/imx8m/ddr_init.c
> @@ -13,14 +13,32 @@
>  #include <mach/imx8m-regs.h>
>  #include <mach/imx8m-ccm-regs.h>
>  
> +bool imx8m_ddr_old_spreadsheet = true;
> +
>  static void ddr_cfg_umctl2(struct dram_cfg_param *ddrc_cfg, int num)
>  {
>  	int i = 0;
>  
>  	for (i = 0; i < num; i++) {
> +		if (ddrc_cfg->reg == DDRC_ADDRMAP7(0))
> +		    imx8m_ddr_old_spreadsheet = false;
>  		reg32_write((unsigned long)ddrc_cfg->reg, ddrc_cfg-
> >val);
>  		ddrc_cfg++;
>  	}
> +
> +	/*
> +	 * Older NXP DDR configuration spreadsheets don't initialize
> ADDRMAP7,
> +	 * which falsifies the memory size read back from the
> controller
> +	 * in barebox proper.
> +	 */
> +	if (imx8m_ddr_old_spreadsheet) {
> +		pr_warn("Working around old spreadsheet. Please
> regenerate\n");
> +		/*
> +		 * Alternatively, stick { DDRC_ADDRMAP7(0), 0xf0f }
> into
> +		 * struct dram_timing_info::ddrc_cfg of your old timing
> file
> +		 */
> +		reg32_write(DDRC_ADDRMAP7(0), 0xf0f);
> +	}
>  }
>  
>  /*
> diff --git a/drivers/ddr/imx8m/helper.c b/drivers/ddr/imx8m/helper.c
> index 94bbb811576d..98e40849584b 100644
> --- a/drivers/ddr/imx8m/helper.c
> +++ b/drivers/ddr/imx8m/helper.c
> @@ -62,6 +62,12 @@ void dram_config_save(struct dram_timing_info
> *timing_info,
>  		cfg++;
>  	}
>  
> +	if (imx8m_ddr_old_spreadsheet) {
> +		cfg->reg = DDRC_ADDRMAP7(0);
> +		cfg->val = 0xf0f;
> +		cfg++;
> +	}
> +
>  	/* save ddrphy config */
>  	saved_timing->ddrphy_cfg = cfg;
>  	for (i = 0; i < timing_info->ddrphy_cfg_num; i++) {
> diff --git a/include/soc/imx8m/ddr.h b/include/soc/imx8m/ddr.h
> index 9ae7cb877686..147a7d499aaf 100644
> --- a/include/soc/imx8m/ddr.h
> +++ b/include/soc/imx8m/ddr.h
> @@ -407,6 +407,7 @@ static inline void reg32setbit(unsigned long
> addr, u32 bit)
>  #define dwc_ddrphy_apb_rd(addr) \
>  	reg32_read(IOMEM(IP2APB_DDRPHY_IPS_BASE_ADDR(0)) + 4 * (addr))
>  
> +extern bool imx8m_ddr_old_spreadsheet;
>  extern struct dram_cfg_param ddrphy_trained_csr[];
>  extern uint32_t ddrphy_trained_csr_num;
>  
-- 
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