On Tue, 2020-12-29 at 16:26 +0200, Laurent Pinchart wrote:
> Hi Ezequiel,
>
> Thank you for the patch.
>
> On Tue, Dec 29, 2020 at 07:31:02AM -0300, Ezequiel Garcia wrote:
> > Currently, the CSI2 subdevice is using the data-lanes from the
> > neareast endpoint to config the CSI2 lanes.
> >
> > While this may work, the proper way to configure the hardware is
> > to obtain the remote subdevice in v4l2_async_notifier_operations.bound(),
> > and then call get_mbus_config using the remote subdevice to get
> > the active lanes.
> >
> > Signed-off-by: Ezequiel Garcia <ezequiel@xxxxxxxxxxxxx>
> > ---
> > drivers/staging/media/imx/TODO | 12 ---
> > drivers/staging/media/imx/imx6-mipi-csi2.c | 101 ++++++++++++++++++---
> > 2 files changed, 90 insertions(+), 23 deletions(-)
> >
> > diff --git a/drivers/staging/media/imx/TODO b/drivers/staging/media/imx/TODO
> > index 9cfc1c1e78dc..c575f419204a 100644
> > --- a/drivers/staging/media/imx/TODO
> > +++ b/drivers/staging/media/imx/TODO
> > @@ -2,18 +2,6 @@
> > - The Frame Interval Monitor could be exported to v4l2-core for
> > general use.
> >
> > -- The CSI subdevice parses its nearest upstream neighbor's device-tree
> > - bus config in order to setup the CSI. Laurent Pinchart argues that
> > - instead the CSI subdev should call its neighbor's g_mbus_config op
> > - (which should be propagated if necessary) to get this info. However
> > - Hans Verkuil is planning to remove the g_mbus_config op. For now this
> > - driver uses the parsed DT bus config method until this issue is
> > - resolved.
> > -
> > - 2020-06: g_mbus has been removed in favour of the get_mbus_config pad
> > - operation which should be used to avoid parsing the remote endpoint
> > - configuration.
> > -
> > - This media driver supports inheriting V4L2 controls to the
> > video capture devices, from the subdevices in the capture device's
> > pipeline. The controls for each capture device are updated in the
> > diff --git a/drivers/staging/media/imx/imx6-mipi-csi2.c b/drivers/staging/media/imx/imx6-mipi-csi2.c
> > index 94d87d27d389..bf6a61dd34c2 100644
> > --- a/drivers/staging/media/imx/imx6-mipi-csi2.c
> > +++ b/drivers/staging/media/imx/imx6-mipi-csi2.c
> > @@ -42,7 +42,10 @@ struct csi2_dev {
> > struct clk *pllref_clk;
> > struct clk *pix_clk; /* what is this? */
> > void __iomem *base;
> > - struct v4l2_fwnode_bus_mipi_csi2 bus;
> > +
> > + struct v4l2_subdev *remote;
> > + unsigned int remote_pad;
> > + unsigned short data_lanes;
> >
> > /* lock to protect all members below */
> > struct mutex lock;
> > @@ -138,10 +141,8 @@ static void csi2_enable(struct csi2_dev *csi2, bool enable)
> > }
> > }
> >
> > -static void csi2_set_lanes(struct csi2_dev *csi2)
> > +static void csi2_set_lanes(struct csi2_dev *csi2, unsigned int lanes)
> > {
> > - int lanes = csi2->bus.num_data_lanes;
> > -
> > writel(lanes - 1, csi2->base + CSI2_N_LANES);
> > }
> >
> > @@ -250,12 +251,13 @@ static int __maybe_unused csi2_dphy_wait_ulp(struct csi2_dev *csi2)
> > }
> >
> > /* Waits for low-power LP-11 state on data and clock lanes. */
> > -static void csi2_dphy_wait_stopstate(struct csi2_dev *csi2)
> > +static void csi2_dphy_wait_stopstate(struct csi2_dev *csi2,
> > + unsigned int lanes)
> > {
> > u32 mask, reg;
> > int ret;
> >
> > - mask = PHY_STOPSTATECLK | (((1 << csi2->bus.num_data_lanes) - 1) <<
> > + mask = PHY_STOPSTATECLK | (((1 << lanes) - 1) <<
> > PHY_STOPSTATEDATA_BIT);
>
> This now holds on a single line.
>
> >
> > ret = readl_poll_timeout(csi2->base + CSI2_PHY_STATE, reg,
> > @@ -300,8 +302,56 @@ static void csi2ipu_gasket_init(struct csi2_dev *csi2)
> > writel(reg, csi2->base + CSI2IPU_GASKET);
> > }
> >
> > +static int csi2_get_active_lanes(struct csi2_dev *csi2, unsigned int *lanes)
>
> The function could return the number of lanes, instead of using an
> output parameter. Up to you.
>
Do you think the checks (num_lanes > csi2->data_lanes, and
type != V4L2_MBUS_CSI2_DPHY) should be moved out
of the function?
> > +{
> > + struct v4l2_mbus_config mbus_config = { 0 };
> > + unsigned int num_lanes = UINT_MAX;
> > + int ret;
> > +
> > + *lanes = csi2->data_lanes;
> > +
> > + ret = v4l2_subdev_call(csi2->remote, pad, get_mbus_config,
> > + csi2->remote_pad, &mbus_config);
> > + if (ret == -ENOIOCTLCMD) {
> > + dev_dbg(csi2->dev, "No remote mbus configuration available\n");
> > + return 0;
> > + }
> > +
> > + if (ret) {
> > + dev_err(csi2->dev, "Failed to get remote mbus configuration\n");
> > + return ret;
> > + }
> > +
> > + if (mbus_config.type != V4L2_MBUS_CSI2_DPHY) {
> > + dev_err(csi2->dev, "Unsupported media bus type %u\n",
> > + mbus_config.type);
> > + return -EINVAL;
> > + }
> > +
> > + if (mbus_config.flags & V4L2_MBUS_CSI2_1_LANE)
> > + num_lanes = 1;
> > + else if (mbus_config.flags & V4L2_MBUS_CSI2_2_LANE)
> > + num_lanes = 2;
> > + else if (mbus_config.flags & V4L2_MBUS_CSI2_3_LANE)
> > + num_lanes = 3;
> > + else if (mbus_config.flags & V4L2_MBUS_CSI2_4_LANE)
> > + num_lanes = 4;
> > +
> > + if (num_lanes > csi2->data_lanes) {
> > + dev_err(csi2->dev,
> > + "Unsupported mbus config: too many data lanes %u\n",
> > + num_lanes);
> > + return -EINVAL;
> > + }
> > +
> > + *lanes = num_lanes;
> > +
> > + return 0;
> > +}
>
> It could make sense to move this to a core V4L2 helper, but it can be
> done later.
>
> > +
> > static int csi2_start(struct csi2_dev *csi2)
> > {
> > + unsigned int lanes;
> > int ret;
> >
> > ret = clk_prepare_enable(csi2->pix_clk);
> > @@ -316,12 +366,16 @@ static int csi2_start(struct csi2_dev *csi2)
> > if (ret)
> > goto err_disable_clk;
> >
> > + ret = csi2_get_active_lanes(csi2, &lanes);
> > + if (ret)
> > + goto err_disable_clk;
> > +
> > /* Step 4 */
> > - csi2_set_lanes(csi2);
> > + csi2_set_lanes(csi2, lanes);
> > csi2_enable(csi2, true);
> >
> > /* Step 5 */
> > - csi2_dphy_wait_stopstate(csi2);
> > + csi2_dphy_wait_stopstate(csi2, lanes);
> >
> > /* Step 6 */
> > ret = v4l2_subdev_call(csi2->src_sd, video, s_stream, 1);
> > @@ -544,12 +598,37 @@ static int csi2_notify_bound(struct v4l2_async_notifier *notifier,
> > {
> > struct csi2_dev *csi2 = notifier_to_dev(notifier);
> > struct media_pad *sink = &csi2->sd.entity.pads[CSI2_SINK_PAD];
> > + int pad;
> > +
> > + pad = media_entity_get_fwnode_pad(&sd->entity, asd->match.fwnode,
> > + MEDIA_PAD_FL_SOURCE);
> > + if (pad < 0) {
> > + dev_err(csi2->dev, "Failed to find pad for %s\n", sd->name);
> > + return pad;
> > + }
> > +
> > + csi2->remote = sd;
> > + csi2->remote_pad = pad;
> > +
> > + dev_dbg(csi2->dev, "Bound %s pad: %d\n", sd->name, pad);
> >
> > return v4l2_create_fwnode_links_to_pad(sd, sink);
> > }
> >
> > +static void csi2_notify_unbind(struct v4l2_async_notifier *notifier,
> > + struct v4l2_subdev *sd,
> > + struct v4l2_async_subdev *asd)
> > +{
> > + struct csi2_dev *csi2 = notifier_to_dev(notifier);
> > +
> > + csi2->remote = NULL;
> > +
> > + dev_dbg(csi2->dev, "Unbind %s\n", sd->name);
>
> I'm not sure if this debug message is useful, I think I'd drop it.
>
Sure.
> With these small issues addressed,
>
> Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
>
Thanks,
Ezequiel
