Re: [PATCH 1/3] stm32mp1: ram: add read valid training support

[Patrice CHOTARD <patrice.chotard@foss.st.com>]

Hi Patrick

On 11/15/21 3:32 PM, Patrick Delaunay wrote:
> Add the read data eye training = training for optimal read valid placement
> (RVTRN) when the built-in calibration is executed for LPDDR2 and LPDDR3.
> 
> This training is supported on the PUBL integrated in the STM32MP15x
> DDR subsystem and it is not required for DDR3.
> 
> Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
> ---
> 
>  drivers/ram/stm32mp1/stm32mp1_ddr.c      | 8 ++++++--
>  drivers/ram/stm32mp1/stm32mp1_ddr_regs.h | 1 +
>  2 files changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/ram/stm32mp1/stm32mp1_ddr.c b/drivers/ram/stm32mp1/stm32mp1_ddr.c
> index 0457166b12..1f8422518b 100644
> --- a/drivers/ram/stm32mp1/stm32mp1_ddr.c
> +++ b/drivers/ram/stm32mp1/stm32mp1_ddr.c
> @@ -826,8 +826,12 @@ start:
>   */
>  
>  /* 10. configure PUBL PIR register to specify which training step to run */
> -	/* warning : RVTRN  is not supported by this PUBL */
> -		stm32mp1_ddrphy_init(priv->phy, DDRPHYC_PIR_QSTRN);
> +		/* RVTRN is excuted only on LPDDR2/LPDDR3 */
> +		if (config->c_reg.mstr & DDRCTRL_MSTR_DDR3)
> +			pir = DDRPHYC_PIR_QSTRN;
> +		else
> +			pir = DDRPHYC_PIR_QSTRN | DDRPHYC_PIR_RVTRN;
> +		stm32mp1_ddrphy_init(priv->phy, pir);
>  
>  /* 11. monitor PUB PGSR.IDONE to poll cpmpletion of training sequence */
>  		ddrphy_idone_wait(priv->phy);
> diff --git a/drivers/ram/stm32mp1/stm32mp1_ddr_regs.h b/drivers/ram/stm32mp1/stm32mp1_ddr_regs.h
> index 3c8885a965..ada3087328 100644
> --- a/drivers/ram/stm32mp1/stm32mp1_ddr_regs.h
> +++ b/drivers/ram/stm32mp1/stm32mp1_ddr_regs.h
> @@ -309,6 +309,7 @@ struct stm32mp1_ddrphy {
>  #define DDRPHYC_PIR_DRAMRST			BIT(5)
>  #define DDRPHYC_PIR_DRAMINIT			BIT(6)
>  #define DDRPHYC_PIR_QSTRN			BIT(7)
> +#define DDRPHYC_PIR_RVTRN			BIT(8)
>  #define DDRPHYC_PIR_ICPC			BIT(16)
>  #define DDRPHYC_PIR_ZCALBYP			BIT(30)
>  #define DDRPHYC_PIR_INITSTEPS_MASK		GENMASK(31, 7)
> 
Reviewed-by: Patrice Chotard <patrice.chotard@foss.st.com>
Thanks
Patrice