Re: [PATCH v5] media: rcar-csi2: Correct the selection of hsfreqrange

From: Niklas Söderlund
Date: Tue May 12 2020 - 17:30:51 EST

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Hi Michael and Suresh,

Thanks for your comments Michael.

On 2020-05-04 17:01:22 +0200, Michael Rodin wrote:
> Hello Suresh, Niklas,
>
> I think that we should not change the structs for PHTW register configuration,
> because there are no "max" values in the table "PHTW Set Values" from the
> Renesas Hardware Manual. The patch looks just wrong. A major issue is also
> that the Hardware Manual does not provide any algorithm, how to select the
> right table entry for the configuration of PHTW and PHYPLL registers, so we
> can not say for sure that the patch is correct. It is also not clear, what
> are the "default" bit rates? It looks like they are made exactly for usage
> in driver code:
> - both PHTW and PHYPLL tables have "default" values
> - only PHYPLL (HSFREQRANGE) tables have min/max values and it requires
> additional rounding in order to hardcode them in a driver
> But these are just my speculations. If they are correct, then the only
> exception, where the patch v2 failed, could be a typo in the Hardware Manual.
> Otherwise patch v2 looks much better to me. I think, we should wait for more
> details from Renesas before fixing this issue.

I see your point.

As a middle ground as Suresh is having a real problem and the logic in
the driver is wrong and should be fixed. How about keeping the
definition of the struct rcsi2_mbps_reg as it is but updating all the
tables .mbps values from the default to the max value?

>
> On Thu, Apr 30, 2020 at 03:03:10PM +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@xxxxxxxxxxxxxx>
> > Signed-off-by: Kazuyoshi Akiyama <akiyama@xxxxxxxxxxxxx>
> > ---
> > 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.
> >
> > Changes in v5:
> > - Removed mbps variable in rcsi2_mbps_reg and aligned all
> > tables accordingly
> >
> > drivers/media/platform/rcar-vin/rcar-csi2.c | 282 ++++++++++++++--------------
> > 1 file changed, 141 insertions(+), 141 deletions(-)
> >
> > diff --git a/drivers/media/platform/rcar-vin/rcar-csi2.c b/drivers/media/platform/rcar-vin/rcar-csi2.c
> > index faa9fb2..d45bf80 100644
> > --- a/drivers/media/platform/rcar-vin/rcar-csi2.c
> > +++ b/drivers/media/platform/rcar-vin/rcar-csi2.c
> > @@ -132,63 +132,63 @@ struct phtw_value {
> > };
> >
> > struct rcsi2_mbps_reg {
> > - u16 mbps;
> > u16 reg;
> > + u16 max;
> > };
> >
> > static const struct rcsi2_mbps_reg phtw_mbps_h3_v3h_m3n[] = {
> > - { .mbps = 80, .reg = 0x86 },
> > - { .mbps = 90, .reg = 0x86 },
> > - { .mbps = 100, .reg = 0x87 },
> > - { .mbps = 110, .reg = 0x87 },
> > - { .mbps = 120, .reg = 0x88 },
> > - { .mbps = 130, .reg = 0x88 },
> > - { .mbps = 140, .reg = 0x89 },
> > - { .mbps = 150, .reg = 0x89 },
> > - { .mbps = 160, .reg = 0x8a },
> > - { .mbps = 170, .reg = 0x8a },
> > - { .mbps = 180, .reg = 0x8b },
> > - { .mbps = 190, .reg = 0x8b },
> > - { .mbps = 205, .reg = 0x8c },
> > - { .mbps = 220, .reg = 0x8d },
> > - { .mbps = 235, .reg = 0x8e },
> > - { .mbps = 250, .reg = 0x8e },
> > + { .reg = 0x86, .max = 80 },
> > + { .reg = 0x86, .max = 90 },
> > + { .reg = 0x87, .max = 100 },
> > + { .reg = 0x87, .max = 110 },
> > + { .reg = 0x88, .max = 120 },
> > + { .reg = 0x88, .max = 130 },
> > + { .reg = 0x89, .max = 140 },
> > + { .reg = 0x89, .max = 150 },
> > + { .reg = 0x8a, .max = 160 },
> > + { .reg = 0x8a, .max = 170 },
> > + { .reg = 0x8b, .max = 180 },
> > + { .reg = 0x8b, .max = 190 },
> > + { .reg = 0x8c, .max = 205 },
> > + { .reg = 0x8d, .max = 220 },
> > + { .reg = 0x8e, .max = 235 },
> > + { .reg = 0x8e, .max = 250 },
> > { /* sentinel */ },
> > };
> >
> > static const struct rcsi2_mbps_reg phtw_mbps_v3m_e3[] = {
> > - { .mbps = 80, .reg = 0x00 },
> > - { .mbps = 90, .reg = 0x20 },
> > - { .mbps = 100, .reg = 0x40 },
> > - { .mbps = 110, .reg = 0x02 },
> > - { .mbps = 130, .reg = 0x22 },
> > - { .mbps = 140, .reg = 0x42 },
> > - { .mbps = 150, .reg = 0x04 },
> > - { .mbps = 170, .reg = 0x24 },
> > - { .mbps = 180, .reg = 0x44 },
> > - { .mbps = 200, .reg = 0x06 },
> > - { .mbps = 220, .reg = 0x26 },
> > - { .mbps = 240, .reg = 0x46 },
> > - { .mbps = 250, .reg = 0x08 },
> > - { .mbps = 270, .reg = 0x28 },
> > - { .mbps = 300, .reg = 0x0a },
> > - { .mbps = 330, .reg = 0x2a },
> > - { .mbps = 360, .reg = 0x4a },
> > - { .mbps = 400, .reg = 0x0c },
> > - { .mbps = 450, .reg = 0x2c },
> > - { .mbps = 500, .reg = 0x0e },
> > - { .mbps = 550, .reg = 0x2e },
> > - { .mbps = 600, .reg = 0x10 },
> > - { .mbps = 650, .reg = 0x30 },
> > - { .mbps = 700, .reg = 0x12 },
> > - { .mbps = 750, .reg = 0x32 },
> > - { .mbps = 800, .reg = 0x52 },
> > - { .mbps = 850, .reg = 0x72 },
> > - { .mbps = 900, .reg = 0x14 },
> > - { .mbps = 950, .reg = 0x34 },
> > - { .mbps = 1000, .reg = 0x54 },
> > - { .mbps = 1050, .reg = 0x74 },
> > - { .mbps = 1125, .reg = 0x16 },
> > + { .reg = 0x00, .max = 80 },
> > + { .reg = 0x20, .max = 90 },
> > + { .reg = 0x40, .max = 100 },
> > + { .reg = 0x02, .max = 110 },
> > + { .reg = 0x22, .max = 130 },
> > + { .reg = 0x42, .max = 140 },
> > + { .reg = 0x04, .max = 150 },
> > + { .reg = 0x24, .max = 170 },
> > + { .reg = 0x44, .max = 180 },
> > + { .reg = 0x06, .max = 200 },
> > + { .reg = 0x26, .max = 220 },
> > + { .reg = 0x46, .max = 240 },
> > + { .reg = 0x08, .max = 250 },
> > + { .reg = 0x28, .max = 270 },
> > + { .reg = 0x0a, .max = 300 },
> > + { .reg = 0x2a, .max = 330 },
> > + { .reg = 0x4a, .max = 360 },
> > + { .reg = 0x0c, .max = 400 },
> > + { .reg = 0x2c, .max = 450 },
> > + { .reg = 0x0e, .max = 500 },
> > + { .reg = 0x2e, .max = 550 },
> > + { .reg = 0x10, .max = 600 },
> > + { .reg = 0x30, .max = 650 },
> > + { .reg = 0x12, .max = 700 },
> > + { .reg = 0x32, .max = 750 },
> > + { .reg = 0x52, .max = 800 },
> > + { .reg = 0x72, .max = 850 },
> > + { .reg = 0x14, .max = 900 },
> > + { .reg = 0x34, .max = 950 },
> > + { .reg = 0x54, .max = 1000 },
> > + { .reg = 0x74, .max = 1050 },
> > + { .reg = 0x16, .max = 1125 },
> > { /* sentinel */ },
> > };
> >
> > @@ -201,96 +201,96 @@ 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 +432,11 @@ 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;
> > }
> > @@ -907,11 +907,11 @@ static int rcsi2_phtw_write_mbps(struct rcar_csi2 *priv, unsigned int mbps,
> > {
> > const struct rcsi2_mbps_reg *value;
> >
> > - for (value = values; value->mbps; value++)
> > - if (value->mbps >= mbps)
> > + for (value = values; value->max; value++)
> > + if (value->max >= mbps)
> > break;
> >
> > - if (!value->mbps) {
> > + if (!value->max) {
> > dev_err(priv->dev, "Unsupported PHY speed (%u Mbps)", mbps);
> > return -ERANGE;
> > }
> > --
> > 2.7.4
> >
>
> --
> Best Regards,
> Michael

--
Regards,
Niklas Söderlund

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