Hi Laurent,
Thanks for your feedback.
On 2019-03-11 11:53:51 +0200, Laurent Pinchart wrote:
> Hi Niklas,
>
> Thank you for the patch.
>
> On Sat, Mar 09, 2019 at 12:47:22AM +0100, Niklas Söderlund wrote:
> > Later versions of the datasheet updates the reset procedure to more
> > closely resemble the standby mode. Update the driver to enter and exit
> > the standby mode instead of resetting the hardware before and after
> > streaming is started and stopped.
>
> I was mislead thinking this added support for module reset in addition
> to software reset (SRST_SRST-, but it actually removes the software
> reset completely. Should the commit message make this clear ?
Good point, will add a clarification in next version.
>
> > While at it break out the full start and stop procedures from
> > rcsi2_s_stream() into the existing helper functions.
> >
> > Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@xxxxxxxxxxxx>
> > ---
> > drivers/media/platform/rcar-vin/Kconfig | 1 +
> > drivers/media/platform/rcar-vin/rcar-csi2.c | 69 +++++++++++++--------
> > 2 files changed, 43 insertions(+), 27 deletions(-)
> >
> > diff --git a/drivers/media/platform/rcar-vin/Kconfig b/drivers/media/platform/rcar-vin/Kconfig
> > index e3eb8fee253658da..f26f47e3bcf44825 100644
> > --- a/drivers/media/platform/rcar-vin/Kconfig
> > +++ b/drivers/media/platform/rcar-vin/Kconfig
> > @@ -3,6 +3,7 @@ config VIDEO_RCAR_CSI2
> > tristate "R-Car MIPI CSI-2 Receiver"
> > depends on VIDEO_V4L2 && VIDEO_V4L2_SUBDEV_API && OF
> > depends on ARCH_RENESAS || COMPILE_TEST
> > + select RESET_CONTROLLER
> > select V4L2_FWNODE
> > help
> > Support for Renesas R-Car MIPI CSI-2 receiver.
> > diff --git a/drivers/media/platform/rcar-vin/rcar-csi2.c b/drivers/media/platform/rcar-vin/rcar-csi2.c
> > index f64528d2be3c95dd..7a1c9b549e0fffc6 100644
> > --- a/drivers/media/platform/rcar-vin/rcar-csi2.c
> > +++ b/drivers/media/platform/rcar-vin/rcar-csi2.c
> > @@ -14,6 +14,7 @@
> > #include <linux/of_graph.h>
> > #include <linux/platform_device.h>
> > #include <linux/pm_runtime.h>
> > +#include <linux/reset.h>
> > #include <linux/sys_soc.h>
> >
> > #include <media/v4l2-ctrls.h>
> > @@ -350,6 +351,7 @@ struct rcar_csi2 {
> > struct device *dev;
> > void __iomem *base;
> > const struct rcar_csi2_info *info;
> > + struct reset_control *rstc;
> >
> > struct v4l2_subdev subdev;
> > struct media_pad pads[NR_OF_RCAR_CSI2_PAD];
> > @@ -387,11 +389,19 @@ static void rcsi2_write(struct rcar_csi2 *priv, unsigned int reg, u32 data)
> > iowrite32(data, priv->base + reg);
> > }
> >
> > -static void rcsi2_reset(struct rcar_csi2 *priv)
> > +static void rcsi2_enter_standby(struct rcar_csi2 *priv)
> > {
> > - rcsi2_write(priv, SRST_REG, SRST_SRST);
> > + rcsi2_write(priv, PHYCNT_REG, 0);
> > + rcsi2_write(priv, PHTC_REG, PHTC_TESTCLR);
> > + reset_control_assert(priv->rstc);
> > usleep_range(100, 150);
> > - rcsi2_write(priv, SRST_REG, 0);
> > + pm_runtime_put(priv->dev);
> > +}
> > +
> > +static void rcsi2_exit_standby(struct rcar_csi2 *priv)
> > +{
> > + pm_runtime_get_sync(priv->dev);
> > + reset_control_deassert(priv->rstc);
> > }
> >
> > static int rcsi2_wait_phy_start(struct rcar_csi2 *priv)
> > @@ -462,7 +472,7 @@ static int rcsi2_calc_mbps(struct rcar_csi2 *priv, unsigned int bpp)
> > return mbps;
> > }
> >
> > -static int rcsi2_start(struct rcar_csi2 *priv)
> > +static int rcsi2_start_receiver(struct rcar_csi2 *priv)
> > {
> > const struct rcar_csi2_format *format;
> > u32 phycnt, vcdt = 0, vcdt2 = 0;
> > @@ -506,7 +516,6 @@ static int rcsi2_start(struct rcar_csi2 *priv)
> >
> > /* Init */
> > rcsi2_write(priv, TREF_REG, TREF_TREF);
> > - rcsi2_reset(priv);
> > rcsi2_write(priv, PHTC_REG, 0);
> >
> > /* Configure */
> > @@ -564,19 +573,36 @@ static int rcsi2_start(struct rcar_csi2 *priv)
> > return 0;
> > }
> >
> > +static int rcsi2_start(struct rcar_csi2 *priv)
> > +{
> > + int ret;
> > +
> > + rcsi2_exit_standby(priv);
> > +
> > + ret = rcsi2_start_receiver(priv);
>
> The rcsi2_start_receiver() function should be split in two, with
> rcsi2_wait_phy_start() and below being performed after starting the
> source. Alternatively you could start the source first, but I think a
> split would be better.
I don't think that would work nor is correct. In Figure 25.16.1.1 data
transfer should be started after confirmation of PHY start. If we call
s_stream on the source before confirming PHY start we will never be able
to detect LP-11.
I interpret the diagram as the CSI-2 transmitter should be powered on
before conforming PHY start, something that should happen in s_power not
s_stream. We handle s_power correctly today using the v4l2-mc link
handling so I believe the current code is correct.
Would you agree with my reasoning?
>
> > + if (ret) {
> > + rcsi2_enter_standby(priv);
> > + return ret;
> > + }
> > +
> > + ret = v4l2_subdev_call(priv->remote, video, s_stream, 1);
> > + if (ret) {
> > + rcsi2_enter_standby(priv);
> > + return ret;
> > + }
> > +
> > + return 0;
> > +}
> > +
> > static void rcsi2_stop(struct rcar_csi2 *priv)
> > {
> > - rcsi2_write(priv, PHYCNT_REG, 0);
> > -
> > - rcsi2_reset(priv);
> > -
> > - rcsi2_write(priv, PHTC_REG, PHTC_TESTCLR);
> > + v4l2_subdev_call(priv->remote, video, s_stream, 0);
> > + rcsi2_enter_standby(priv);
>
> Shouldn't you enter standby before stopping the source ? Otherwise
> there's a risk of CSI errors being detected. Figures 25.23.1 and 25.23.2
> seem to agree with me.
I agree with you on this, it should enter standby before stopping the
source. Will change this for next version.
>
> > }
> >
> > static int rcsi2_s_stream(struct v4l2_subdev *sd, int enable)
> > {
> > struct rcar_csi2 *priv = sd_to_csi2(sd);
> > - struct v4l2_subdev *nextsd;
> > int ret = 0;
> >
> > mutex_lock(&priv->lock);
> > @@ -586,27 +612,12 @@ static int rcsi2_s_stream(struct v4l2_subdev *sd, int enable)
> > goto out;
> > }
> >
> > - nextsd = priv->remote;
> > -
> > if (enable && priv->stream_count == 0) {
> > - pm_runtime_get_sync(priv->dev);
> > -
> > ret = rcsi2_start(priv);
> > - if (ret) {
> > - pm_runtime_put(priv->dev);
> > + if (ret)
> > goto out;
> > - }
> > -
> > - ret = v4l2_subdev_call(nextsd, video, s_stream, 1);
> > - if (ret) {
> > - rcsi2_stop(priv);
> > - pm_runtime_put(priv->dev);
> > - goto out;
> > - }
> > } else if (!enable && priv->stream_count == 1) {
> > rcsi2_stop(priv);
> > - v4l2_subdev_call(nextsd, video, s_stream, 0);
> > - pm_runtime_put(priv->dev);
> > }
> >
> > priv->stream_count += enable ? 1 : -1;
> > @@ -936,6 +947,10 @@ static int rcsi2_probe_resources(struct rcar_csi2 *priv,
> > if (irq < 0)
> > return irq;
> >
> > + priv->rstc = devm_reset_control_get(&pdev->dev, NULL);
> > + if (IS_ERR(priv->rstc))
> > + return PTR_ERR(priv->rstc);
> > +
> > return 0;
> > }
> >
>
> --
> Regards,
>
> Laurent Pinchart
--
Regards,
Niklas Söderlund
