Re: [PATCH v2 09/10] sunxi: Parameterize some of H616 DDR3 timings

[Andre Przywara <andre.przywara@arm.com>]

On Mon, 10 Apr 2023 10:21:18 +0200
Jernej Skrabec <jernej.skrabec@gmail.com> wrote:

> Currently twr2rd, trd2wr and twtp are constants, but according to
> vendor driver they are calculated from other values. Do that here too,
> in preparation for later introduction of new parameter.
> 
> While at it, introduce constant for t_wr_lat, which was incorrectly
> calculated from tcl before.
> 
> Signed-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>

The transformations look correct, though I cannot really judge their
meanings. Nevertheless:

Reviewed-by: Andre Przywara <andre.przywara@arm.com>

Cheers,
Andre

> ---
>  arch/arm/mach-sunxi/dram_timings/h616_ddr3_1333.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/arm/mach-sunxi/dram_timings/h616_ddr3_1333.c b/arch/arm/mach-sunxi/dram_timings/h616_ddr3_1333.c
> index 8f508344bc17..f109e920820b 100644
> --- a/arch/arm/mach-sunxi/dram_timings/h616_ddr3_1333.c
> +++ b/arch/arm/mach-sunxi/dram_timings/h616_ddr3_1333.c
> @@ -48,10 +48,11 @@ void mctl_set_timing_params(struct dram_para *para)
>  	u8 tcl		= 7;			/* JEDEC: CL / 2 => 6 */
>  	u8 tcwl		= 5;			/* JEDEC: 8 */
>  	u8 t_rdata_en	= 9;			/* ? */
> +	u8 t_wr_lat	= 5;			/* ? */
>  
> -	u8 twtp		= 14;			/* (WL + BL / 2 + tWR) / 2 */
> -	u8 twr2rd	= trtp + 7;		/* (WL + BL / 2 + tWTR) / 2 */
> -	u8 trd2wr	= 5;			/* (RL + BL / 2 + 2 - WL) / 2 */
> +	u8 twtp		= tcl + 2 + tcwl;	/* (WL + BL / 2 + tWR) / 2 */
> +	u8 twr2rd	= trtp + 2 + tcwl;	/* (WL + BL / 2 + tWTR) / 2 */
> +	u8 trd2wr	= tcl + 3 - tcwl;	/* (RL + BL / 2 + 2 - WL) / 2 */
>  
>  	/* set DRAM timing */
>  	writel((twtp << 24) | (tfaw << 16) | (trasmax << 8) | tras,
> @@ -85,7 +86,7 @@ void mctl_set_timing_params(struct dram_para *para)
>  	clrsetbits_le32(&mctl_ctl->rankctl, 0xff0, 0x660);
>  
>  	/* Configure DFI timing */
> -	writel((tcl - 2) | 0x2000000 | (t_rdata_en << 16) | 0x808000,
> +	writel(t_wr_lat | 0x2000000 | (t_rdata_en << 16) | 0x808000,
>  	       &mctl_ctl->dfitmg0);
>  	writel(0x100202, &mctl_ctl->dfitmg1);
>