RE: [PATCH] memory: renesas-rpc-if: avoid use of undocumented bits

[Prabhakar Mahadev Lad <prabhakar.mahadev-lad.rj@bp.renesas.com>]

Hi Wolfram,

Thank you for the patch.

> -----Original Message-----
> From: Wolfram Sang <wsa+renesas@sang-engineering.com>
> Sent: 17 November 2021 09:37
> To: linux-renesas-soc@vger.kernel.org
> Cc: Prabhakar Mahadev Lad <prabhakar.mahadev-lad.rj@bp.renesas.com>; Wolfram Sang <wsa+renesas@sang-
> engineering.com>; Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>; linux-
> kernel@vger.kernel.org
> Subject: [PATCH] memory: renesas-rpc-if: avoid use of undocumented bits
> 
> Instead of writing fixed values with undocumented bits which happen to be set on some SoCs, better
> switch to read-modify-write operations changing only bits which are documented. This is way more
> future-proof as we don't know yet how these bits may be on upcoming SoCs.
> 
> Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
> ---
> 
> This patch is based on the Krzysztof's for-next branch as it depends on Prabhakar's G2L additions.
> 
> Tested on a V3U with some debug code verifying that the same values are written before and after the
> patch.
> 
> @Prabhakar: would you be so kind and test this patch on G2L?
> 
Dumped the registers before and after patch, register values do match. Also tested read/write operation on RZ/G2L.

Tested-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>

Cheers,
Prabhakar

>  drivers/memory/renesas-rpc-if.c | 58 +++++++++++++--------------------
>  1 file changed, 22 insertions(+), 36 deletions(-)
> 
> diff --git a/drivers/memory/renesas-rpc-if.c b/drivers/memory/renesas-rpc-if.c index
> 8c51145c0f5c..a9f3e7bdddf8 100644
> --- a/drivers/memory/renesas-rpc-if.c
> +++ b/drivers/memory/renesas-rpc-if.c
> @@ -20,7 +20,6 @@
> 
>  #define RPCIF_CMNCR		0x0000	/* R/W */
>  #define RPCIF_CMNCR_MD		BIT(31)
> -#define RPCIF_CMNCR_SFDE	BIT(24) /* undocumented but must be set */
>  #define RPCIF_CMNCR_MOIIO3(val)	(((val) & 0x3) << 22)
>  #define RPCIF_CMNCR_MOIIO2(val)	(((val) & 0x3) << 20)
>  #define RPCIF_CMNCR_MOIIO1(val)	(((val) & 0x3) << 18)
> @@ -290,49 +289,36 @@ int rpcif_hw_init(struct rpcif *rpc, bool hyperflash)
>  		rpcif_rzg2l_timing_adjust_sdr(rpc);
>  	}
> 
> -	/*
> -	 * NOTE: The 0x260 are undocumented bits, but they must be set.
> -	 *	 RPCIF_PHYCNT_STRTIM is strobe timing adjustment bits,
> -	 *	 0x0 : the delay is biggest,
> -	 *	 0x1 : the delay is 2nd biggest,
> -	 *	 On H3 ES1.x, the value should be 0, while on others,
> -	 *	 the value should be 7.
> -	 */
> -	if (rpc->type == RPCIF_RCAR_GEN3) {
> -		regmap_write(rpc->regmap, RPCIF_PHYCNT, RPCIF_PHYCNT_STRTIM(7) |
> -			     RPCIF_PHYCNT_PHYMEM(hyperflash ? 3 : 0) | 0x260);
> -	} else {
> -		regmap_read(rpc->regmap, RPCIF_PHYCNT, &dummy);
> -		dummy &= ~RPCIF_PHYCNT_PHYMEM_MASK;
> -		dummy |= RPCIF_PHYCNT_PHYMEM(hyperflash ? 3 : 0) | 0x260;
> -		regmap_write(rpc->regmap, RPCIF_PHYCNT, dummy);
> -	}
> +	regmap_update_bits(rpc->regmap, RPCIF_PHYCNT, RPCIF_PHYCNT_PHYMEM_MASK,
> +			   RPCIF_PHYCNT_PHYMEM(hyperflash ? 3 : 0));
> +
> +	if (rpc->type == RPCIF_RCAR_GEN3)
> +		regmap_update_bits(rpc->regmap, RPCIF_PHYCNT,
> +				   RPCIF_PHYCNT_STRTIM(7), RPCIF_PHYCNT_STRTIM(7));
> 
> -	/*
> -	 * NOTE: The 0x1511144 are undocumented bits, but they must be set
> -	 *       for RPCIF_PHYOFFSET1.
> -	 *	 The 0x31 are undocumented bits, but they must be set
> -	 *	 for RPCIF_PHYOFFSET2.
> -	 */
> -	regmap_write(rpc->regmap, RPCIF_PHYOFFSET1, 0x1511144 |
> -		     RPCIF_PHYOFFSET1_DDRTMG(3));
> -	regmap_write(rpc->regmap, RPCIF_PHYOFFSET2, 0x31 |
> -		     RPCIF_PHYOFFSET2_OCTTMG(4));
> +	regmap_update_bits(rpc->regmap, RPCIF_PHYOFFSET1, RPCIF_PHYOFFSET1_DDRTMG(3),
> +			   RPCIF_PHYOFFSET1_DDRTMG(3));
> +	regmap_update_bits(rpc->regmap, RPCIF_PHYOFFSET2, RPCIF_PHYOFFSET2_OCTTMG(7),
> +			   RPCIF_PHYOFFSET2_OCTTMG(4));
> 
>  	if (hyperflash)
>  		regmap_update_bits(rpc->regmap, RPCIF_PHYINT,
>  				   RPCIF_PHYINT_WPVAL, 0);
> 
>  	if (rpc->type == RPCIF_RCAR_GEN3)
> -		regmap_write(rpc->regmap, RPCIF_CMNCR, RPCIF_CMNCR_SFDE |
> -			     RPCIF_CMNCR_MOIIO_HIZ | RPCIF_CMNCR_IOFV_HIZ |
> -			     RPCIF_CMNCR_BSZ(hyperflash ? 1 : 0));
> +		regmap_update_bits(rpc->regmap, RPCIF_CMNCR,
> +				   RPCIF_CMNCR_MOIIO_HIZ | RPCIF_CMNCR_BSZ(3),
> +				   RPCIF_CMNCR_MOIIO_HIZ |
> +				   RPCIF_CMNCR_BSZ(hyperflash ? 1 : 0));
>  	else
> -		regmap_write(rpc->regmap, RPCIF_CMNCR, RPCIF_CMNCR_SFDE |
> -			     RPCIF_CMNCR_MOIIO3(1) | RPCIF_CMNCR_MOIIO2(1) |
> -			     RPCIF_CMNCR_MOIIO1(1) | RPCIF_CMNCR_MOIIO0(1) |
> -			     RPCIF_CMNCR_IO3FV(2) | RPCIF_CMNCR_IO2FV(2) |
> -			     RPCIF_CMNCR_IO0FV(2) | RPCIF_CMNCR_BSZ(hyperflash ? 1 : 0));
> +		regmap_update_bits(rpc->regmap, RPCIF_CMNCR,
> +				   RPCIF_CMNCR_MOIIO_HIZ | RPCIF_CMNCR_IOFV_HIZ |
> +				   RPCIF_CMNCR_BSZ(3),
> +				   RPCIF_CMNCR_MOIIO3(1) | RPCIF_CMNCR_MOIIO2(1) |
> +				   RPCIF_CMNCR_MOIIO1(1) | RPCIF_CMNCR_MOIIO0(1) |
> +				   RPCIF_CMNCR_IO3FV(2) | RPCIF_CMNCR_IO2FV(2) |
> +				   RPCIF_CMNCR_IO0FV(2) |
> +				   RPCIF_CMNCR_BSZ(hyperflash ? 1 : 0));
> 
>  	/* Set RCF after BSZ update */
>  	regmap_write(rpc->regmap, RPCIF_DRCR, RPCIF_DRCR_RCF);
> --
> 2.30.2