Re: [PATCH v4] media: rcar-csi2: Correct the selection of hsfreqrange

["Niklas Söderlund" <niklas.soderlund@ragnatech.se>]

Hello Suresh,

Thanks for your patch.

On 2020-03-23 13:48:44 +0900, Suresh Udipi wrote:
> hsfreqrange should be chosen based on the calculated mbps which
> is within the range as per table[1]. But current calculation
> always selects first value which is greater than or equal to the
> calculated mbps which may lead to chosing a wrong range in some cases.
> 
> For example for 360 mbps for H3/M3N
> Existing logic selects
> Calculated value 360Mbps : Default 400Mbps Range [368.125 -433.125 mbps]
> 
> This hsfreqrange is out of range.
> 
> The logic is changed to select the first hsfreqrange whose max range[1] is
> greater than the calculated bit rate.
> 
> Calculated value 360Mbps : max range 380.625 mbps is selected
>  i.e Default 350Mbps  Range [320.625 -380.625 mpbs]
> 
> [1] specs r19uh0105ej0200-r-car-3rd-generation.pdf [Table 25.9]
> 
> Fixes: 769afd212b16 ("media: rcar-csi2: add Renesas R-Car MIPI CSI-2 receiver driver")
> 
> Signed-off-by: Suresh Udipi <sudipi@jp.adit-jv.com>
> Signed-off-by: Kazuyoshi Akiyama <akiyama@nds-osk.co.jp>
> ---
>  Changes in v2:
>   - Added the boundary check for the maximum bit rate.
> 
>   - Simplified the logic by remmoving range check
>     as only the closest default value covers most
>     of the use cases.
> 
>   - Aligning the commit message based on the above change
> 
> 
>  Changes in v3:
>     - Added max member from struct rcsi2_mbps_reg.
>       mbps varialbe cannot be removed from rcsi2_mbps_reg,
>       since this structure is reused for
>       phtw_mbps_h3_v3h_m3n/phtw_mbps_v3m_e3 where mbps is
>       used.
> 
> 
>    -  Update the walk of the array in rcsi2_set_phypll() so that it finds
>       the first entry where the calculated bit rate is less than the max.
> 
>    - Support lower bit rates less than 80Mbps like 48Mbps
>      (Raspberry pi camera 640x480 connected to Kingfisher)
>      can also be supported by selecting the lowest default bit rate 80Mbps
>      as done before this fix
> 
>    - Alignement of the commit message based on above changes.
> 
>  Changes in v4:
>   -  Remove unncessary braces.
> 
>  drivers/media/platform/rcar-vin/rcar-csi2.c | 179 ++++++++++++++--------------
>  1 file changed, 90 insertions(+), 89 deletions(-)
> 
> diff --git a/drivers/media/platform/rcar-vin/rcar-csi2.c b/drivers/media/platform/rcar-vin/rcar-csi2.c
> index faa9fb2..ca0321d 100644
> --- a/drivers/media/platform/rcar-vin/rcar-csi2.c
> +++ b/drivers/media/platform/rcar-vin/rcar-csi2.c
> @@ -134,6 +134,7 @@ struct phtw_value {
>  struct rcsi2_mbps_reg {
>  	u16 mbps;

You should remove the mbps field and then update the other tables with 
the max value. Apart from this I like this patch, nice work.

>  	u16 reg;
> +	u16 max;
>  };
>  
>  static const struct rcsi2_mbps_reg phtw_mbps_h3_v3h_m3n[] = {
> @@ -201,96 +202,96 @@ static const struct rcsi2_mbps_reg phtw_mbps_v3m_e3[] = {
>  #define PHYPLL_HSFREQRANGE(n)		((n) << 16)
>  
>  static const struct rcsi2_mbps_reg hsfreqrange_h3_v3h_m3n[] = {
> -	{ .mbps =   80, .reg = 0x00 },
> -	{ .mbps =   90, .reg = 0x10 },
> -	{ .mbps =  100, .reg = 0x20 },
> -	{ .mbps =  110, .reg = 0x30 },
> -	{ .mbps =  120, .reg = 0x01 },
> -	{ .mbps =  130, .reg = 0x11 },
> -	{ .mbps =  140, .reg = 0x21 },
> -	{ .mbps =  150, .reg = 0x31 },
> -	{ .mbps =  160, .reg = 0x02 },
> -	{ .mbps =  170, .reg = 0x12 },
> -	{ .mbps =  180, .reg = 0x22 },
> -	{ .mbps =  190, .reg = 0x32 },
> -	{ .mbps =  205, .reg = 0x03 },
> -	{ .mbps =  220, .reg = 0x13 },
> -	{ .mbps =  235, .reg = 0x23 },
> -	{ .mbps =  250, .reg = 0x33 },
> -	{ .mbps =  275, .reg = 0x04 },
> -	{ .mbps =  300, .reg = 0x14 },
> -	{ .mbps =  325, .reg = 0x25 },
> -	{ .mbps =  350, .reg = 0x35 },
> -	{ .mbps =  400, .reg = 0x05 },
> -	{ .mbps =  450, .reg = 0x16 },
> -	{ .mbps =  500, .reg = 0x26 },
> -	{ .mbps =  550, .reg = 0x37 },
> -	{ .mbps =  600, .reg = 0x07 },
> -	{ .mbps =  650, .reg = 0x18 },
> -	{ .mbps =  700, .reg = 0x28 },
> -	{ .mbps =  750, .reg = 0x39 },
> -	{ .mbps =  800, .reg = 0x09 },
> -	{ .mbps =  850, .reg = 0x19 },
> -	{ .mbps =  900, .reg = 0x29 },
> -	{ .mbps =  950, .reg = 0x3a },
> -	{ .mbps = 1000, .reg = 0x0a },
> -	{ .mbps = 1050, .reg = 0x1a },
> -	{ .mbps = 1100, .reg = 0x2a },
> -	{ .mbps = 1150, .reg = 0x3b },
> -	{ .mbps = 1200, .reg = 0x0b },
> -	{ .mbps = 1250, .reg = 0x1b },
> -	{ .mbps = 1300, .reg = 0x2b },
> -	{ .mbps = 1350, .reg = 0x3c },
> -	{ .mbps = 1400, .reg = 0x0c },
> -	{ .mbps = 1450, .reg = 0x1c },
> -	{ .mbps = 1500, .reg = 0x2c },
> +	{ .reg = 0x00, .max =   97 },
> +	{ .reg = 0x10, .max =  107 },
> +	{ .reg = 0x20, .max =  118 },
> +	{ .reg = 0x30, .max =  128 },
> +	{ .reg = 0x01, .max =  139 },
> +	{ .reg = 0x11, .max =  149 },
> +	{ .reg = 0x21, .max =  160 },
> +	{ .reg = 0x31, .max =  170 },
> +	{ .reg = 0x02, .max =  181 },
> +	{ .reg = 0x12, .max =  191 },
> +	{ .reg = 0x22, .max =  202 },
> +	{ .reg = 0x32, .max =  212 },
> +	{ .reg = 0x03, .max =  228 },
> +	{ .reg = 0x13, .max =  224 },
> +	{ .reg = 0x23, .max =  259 },
> +	{ .reg = 0x33, .max =  275 },
> +	{ .reg = 0x04, .max =  301 },
> +	{ .reg = 0x14, .max =  328 },
> +	{ .reg = 0x25, .max =  354 },
> +	{ .reg = 0x35, .max =  380 },
> +	{ .reg = 0x05, .max =  433 },
> +	{ .reg = 0x16, .max =  485 },
> +	{ .reg = 0x26, .max =  538 },
> +	{ .reg = 0x37, .max =  590 },
> +	{ .reg = 0x07, .max =  643 },
> +	{ .reg = 0x18, .max =  695 },
> +	{ .reg = 0x28, .max =  748 },
> +	{ .reg = 0x39, .max =  800 },
> +	{ .reg = 0x09, .max =  853 },
> +	{ .reg = 0x19, .max =  905 },
> +	{ .reg = 0x29, .max =  958 },
> +	{ .reg = 0x3a, .max = 1010 },
> +	{ .reg = 0x0a, .max = 1063 },
> +	{ .reg = 0x1a, .max = 1115 },
> +	{ .reg = 0x2a, .max = 1168 },
> +	{ .reg = 0x3b, .max = 1220 },
> +	{ .reg = 0x0b, .max = 1273 },
> +	{ .reg = 0x1b, .max = 1325 },
> +	{ .reg = 0x2b, .max = 1378 },
> +	{ .reg = 0x3c, .max = 1430 },
> +	{ .reg = 0x0c, .max = 1483 },
> +	{ .reg = 0x1c, .max = 1500 },
> +	{ .reg = 0x2c, .max = 1500 },
>  	{ /* sentinel */ },
>  };
>  
>  static const struct rcsi2_mbps_reg hsfreqrange_m3w_h3es1[] = {
> -	{ .mbps =   80,	.reg = 0x00 },
> -	{ .mbps =   90,	.reg = 0x10 },
> -	{ .mbps =  100,	.reg = 0x20 },
> -	{ .mbps =  110,	.reg = 0x30 },
> -	{ .mbps =  120,	.reg = 0x01 },
> -	{ .mbps =  130,	.reg = 0x11 },
> -	{ .mbps =  140,	.reg = 0x21 },
> -	{ .mbps =  150,	.reg = 0x31 },
> -	{ .mbps =  160,	.reg = 0x02 },
> -	{ .mbps =  170,	.reg = 0x12 },
> -	{ .mbps =  180,	.reg = 0x22 },
> -	{ .mbps =  190,	.reg = 0x32 },
> -	{ .mbps =  205,	.reg = 0x03 },
> -	{ .mbps =  220,	.reg = 0x13 },
> -	{ .mbps =  235,	.reg = 0x23 },
> -	{ .mbps =  250,	.reg = 0x33 },
> -	{ .mbps =  275,	.reg = 0x04 },
> -	{ .mbps =  300,	.reg = 0x14 },
> -	{ .mbps =  325,	.reg = 0x05 },
> -	{ .mbps =  350,	.reg = 0x15 },
> -	{ .mbps =  400,	.reg = 0x25 },
> -	{ .mbps =  450,	.reg = 0x06 },
> -	{ .mbps =  500,	.reg = 0x16 },
> -	{ .mbps =  550,	.reg = 0x07 },
> -	{ .mbps =  600,	.reg = 0x17 },
> -	{ .mbps =  650,	.reg = 0x08 },
> -	{ .mbps =  700,	.reg = 0x18 },
> -	{ .mbps =  750,	.reg = 0x09 },
> -	{ .mbps =  800,	.reg = 0x19 },
> -	{ .mbps =  850,	.reg = 0x29 },
> -	{ .mbps =  900,	.reg = 0x39 },
> -	{ .mbps =  950,	.reg = 0x0a },
> -	{ .mbps = 1000,	.reg = 0x1a },
> -	{ .mbps = 1050,	.reg = 0x2a },
> -	{ .mbps = 1100,	.reg = 0x3a },
> -	{ .mbps = 1150,	.reg = 0x0b },
> -	{ .mbps = 1200,	.reg = 0x1b },
> -	{ .mbps = 1250,	.reg = 0x2b },
> -	{ .mbps = 1300,	.reg = 0x3b },
> -	{ .mbps = 1350,	.reg = 0x0c },
> -	{ .mbps = 1400,	.reg = 0x1c },
> -	{ .mbps = 1450,	.reg = 0x2c },
> -	{ .mbps = 1500,	.reg = 0x3c },
> +	{ .reg = 0x00, .max =  110 },
> +	{ .reg = 0x10, .max =  120 },
> +	{ .reg = 0x20, .max =  131 },
> +	{ .reg = 0x30, .max =  141 },
> +	{ .reg = 0x01, .max =  152 },
> +	{ .reg = 0x11, .max =  162 },
> +	{ .reg = 0x21, .max =  173 },
> +	{ .reg = 0x31, .max =  183 },
> +	{ .reg = 0x02, .max =  194 },
> +	{ .reg = 0x12, .max =  204 },
> +	{ .reg = 0x22, .max =  215 },
> +	{ .reg = 0x32, .max =  225 },
> +	{ .reg = 0x03, .max =  241 },
> +	{ .reg = 0x13, .max =  257 },
> +	{ .reg = 0x23, .max =  273 },
> +	{ .reg = 0x33, .max =  275 },
> +	{ .reg = 0x04, .max =  301 },
> +	{ .reg = 0x14, .max =  328 },
> +	{ .reg = 0x05, .max =  354 },
> +	{ .reg = 0x15, .max =  393 },
> +	{ .reg = 0x25, .max =  446 },
> +	{ .reg = 0x06, .max =  498 },
> +	{ .reg = 0x16, .max =  551 },
> +	{ .reg = 0x07, .max =  603 },
> +	{ .reg = 0x17, .max =  656 },
> +	{ .reg = 0x08, .max =  708 },
> +	{ .reg = 0x18, .max =  761 },
> +	{ .reg = 0x09, .max =  813 },
> +	{ .reg = 0x19, .max =  866 },
> +	{ .reg = 0x29, .max =  918 },
> +	{ .reg = 0x39, .max =  971 },
> +	{ .reg = 0x0a, .max = 1023 },
> +	{ .reg = 0x1a, .max = 1076 },
> +	{ .reg = 0x2a, .max = 1128 },
> +	{ .reg = 0x3a, .max = 1181 },
> +	{ .reg = 0x0b, .max = 1233 },
> +	{ .reg = 0x1b, .max = 1286 },
> +	{ .reg = 0x2b, .max = 1338 },
> +	{ .reg = 0x3b, .max = 1391 },
> +	{ .reg = 0x0c, .max = 1443 },
> +	{ .reg = 0x1c, .max = 1496 },
> +	{ .reg = 0x2c, .max = 1500 },
> +	{ .reg = 0x3c, .max = 1500 },
>  	{ /* sentinel */ },
>  };
>  
> @@ -432,11 +433,11 @@ static int rcsi2_set_phypll(struct rcar_csi2 *priv, unsigned int mbps)
>  {
>  	const struct rcsi2_mbps_reg *hsfreq;
>  
> -	for (hsfreq = priv->info->hsfreqrange; hsfreq->mbps != 0; hsfreq++)
> -		if (hsfreq->mbps >= mbps)
> +	for (hsfreq = priv->info->hsfreqrange; hsfreq->max != 0; hsfreq++)
> +		if (hsfreq->max >= mbps)
>  			break;
>  
> -	if (!hsfreq->mbps) {
> +	if (!hsfreq->max) {
>  		dev_err(priv->dev, "Unsupported PHY speed (%u Mbps)", mbps);
>  		return -ERANGE;
>  	}
> -- 
> 2.7.4
> 

-- 
Regards,
Niklas Söderlund