Hi Suresh,
Thanks for your work.
On 2020-06-18 19:34:30 +0900, Suresh Udipi wrote:
> hsfreqrange should be chosen based on the calculated mbps which
> is closer to the default bit rate and 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 get the default value which is closest to the
> calculated value [1]
>
> Calculated value 360Mbps : Default 350Mbps Range [320.625 -380.625 mpbs]
>
> [1] specs r19uh0105ej0200-r-car-3rd-generation.pdf [Table 25.9]
>
> Please note that According to Renesas in Table 25.9 the range for
> 220 default value is corrected as below
>
> |Range (Mbps) | Default Bit rate (Mbps) |
> -----------------------------------------------
> | 197.125-244.125 | 220 |
> -----------------------------------------------
>
> 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>
> Signed-off-by: Michael Rodin <mrodin@xxxxxxxxxxxxxx>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@xxxxxxxxxxxx>
> ---
> 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
>
>
> Changes in v6
> - Renesas correct the range of default value 220Mbps. Now
> if we select the nearest value to the default value all
> the values are in range. So reverting back to original patch
>
> - Added warning for values less than Minimum 80Mbps
>
> Changes in v7
> - Create a seperate commit for the warning message less
> than minimum 80Mbps
>
> - Reorder the statements to increase readability
>
> Changes in v8
> - Extended the logic of selection of nearest mbps to
> PHTW registers value less than 250Mbps. A new commit
> is added
>
> drivers/media/platform/rcar-vin/rcar-csi2.c | 9 ++++++++-
> 1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/media/platform/rcar-vin/rcar-csi2.c b/drivers/media/platform/rcar-vin/rcar-csi2.c
> index 151e6a9..f18dedc 100644
> --- a/drivers/media/platform/rcar-vin/rcar-csi2.c
> +++ b/drivers/media/platform/rcar-vin/rcar-csi2.c
> @@ -431,16 +431,23 @@ static int rcsi2_wait_phy_start(struct rcar_csi2 *priv)
> static int rcsi2_set_phypll(struct rcar_csi2 *priv, unsigned int mbps)
> {
> const struct rcsi2_mbps_reg *hsfreq;
> + const struct rcsi2_mbps_reg *hsfreq_prev = NULL;
>
> - for (hsfreq = priv->info->hsfreqrange; hsfreq->mbps != 0; hsfreq++)
> + for (hsfreq = priv->info->hsfreqrange; hsfreq->mbps != 0; hsfreq++) {
> if (hsfreq->mbps >= mbps)
> break;
> + hsfreq_prev = hsfreq;
> + }
>
> if (!hsfreq->mbps) {
> dev_err(priv->dev, "Unsupported PHY speed (%u Mbps)", mbps);
> return -ERANGE;
> }
>
> + if (hsfreq_prev &&
> + ((mbps - hsfreq_prev->mbps) <= (hsfreq->mbps - mbps)))
> + hsfreq = hsfreq_prev;
> +
> rcsi2_write(priv, PHYPLL_REG, PHYPLL_HSFREQRANGE(hsfreq->reg));
>
> return 0;
> --
> 2.7.4
>
--
Regards,
Niklas Söderlund
