| Message ID | 20200913184247.618-1-prabhakar.mahadev-lad.rj@bp.renesas.com |
|---|---|
| Headers | show |
| Series | media: i2c: ov772x: Enable BT656 mode and test pattern support | expand |
Hi Prabhakar, On Sun, Sep 13, 2020 at 07:42:45PM +0100, Lad Prabhakar wrote: > Parse endpoint properties using v4l2_fwnode_endpoint_alloc_parse() > to determine bus-type and store it locally in priv data. > > Also for backward compatibility with the existing DT where bus-type > isnt specified fallback to V4L2_MBUS_PARALLEL. > > Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com> > --- > drivers/media/i2c/ov772x.c | 24 ++++++++++++++++++++++++ > 1 file changed, 24 insertions(+) > > diff --git a/drivers/media/i2c/ov772x.c b/drivers/media/i2c/ov772x.c > index 2cc6a678069a..551082aa7026 100644 > --- a/drivers/media/i2c/ov772x.c > +++ b/drivers/media/i2c/ov772x.c > @@ -31,6 +31,7 @@ > #include <media/v4l2-ctrls.h> > #include <media/v4l2-device.h> > #include <media/v4l2-event.h> > +#include <media/v4l2-fwnode.h> > #include <media/v4l2-image-sizes.h> > #include <media/v4l2-subdev.h> > > @@ -434,6 +435,7 @@ struct ov772x_priv { > #ifdef CONFIG_MEDIA_CONTROLLER > struct media_pad pad; > #endif > + enum v4l2_mbus_type bus_type; > }; > > /* > @@ -1354,6 +1356,8 @@ static const struct v4l2_subdev_ops ov772x_subdev_ops = { > > static int ov772x_probe(struct i2c_client *client) > { > + struct v4l2_fwnode_endpoint bus_cfg = { .bus_type = 0 }; > + struct fwnode_handle *ep; > struct ov772x_priv *priv; > int ret; > static const struct regmap_config ov772x_regmap_config = { > @@ -1415,6 +1419,26 @@ static int ov772x_probe(struct i2c_client *client) > goto error_clk_put; > } > > + ep = fwnode_graph_get_next_endpoint(dev_fwnode(&client->dev), > + NULL); > + if (!ep) { > + dev_err(&client->dev, "endpoint node not found\n"); > + ret = -EINVAL; > + goto error_clk_put; > + } > + > + bus_cfg.bus_type = V4L2_MBUS_PARALLEL; Could you set the bus type when you declare bus_cfg ? There's no point in setting it to UNKNOW and re-writing it here > + ret = v4l2_fwnode_endpoint_alloc_parse(ep, &bus_cfg); Should you here fwnode_handle_put(ep) ? Also, this driver does not support the 'link_frequency' property, as the device does not support CSI-2. As commented on the previous version, the 'alloc' version of v4l2_fwnode_endpoint_parse() reserves space for that property, and requires a manual free like you have here below. So using the 'alloc' version is not techincally wrong, but I don't think it's required here. > + priv->bus_type = bus_cfg.bus_type; > + v4l2_fwnode_endpoint_free(&bus_cfg); > + if (ret) { By reading the code in v4l2-fwnode it seems to me that, if you set bus_cfg.bus_type: 1) The "bus_type" property is set in the fwnode and doesn't match the requested one -> return -ENXIO 2) The "bus_type" property is not set in the fwnode: no error code is returned and vep->bus_type is not changed. > + /* For backward compatibility with the existing DT where > + * bus-type isnt specified fallback to V4L2_MBUS_PARALLEL > + */ This mean there's no need to fallback here, as at this point we only support PARALLEL. If fwnode,bus_type is not set you won't faile, if it's set and doesn't match you should fail as the DT is not correct (at this point). 1) In this patch: try to parse as MBUS_PARALLEL, fail if -ENXIO, assume parallel otherwise and continue. 2) When you introduce BT.656 in the next patch things become nasty. Newer DTS will have bus_type mandatory once my series gets in. Old ones do not and assume "parallel". 2.a) If you try to parse with "cfg.bus_type = MBUS_BT656" and there's no 'bus_type' in the fwnode, the 'parallel' flags are simply cleared at the end of v4l2_fwnode_endpoint_parse_parallel_bus(), but the bus_type does not get changed. You won't detect the mismatch and happily assume the bus type is BT.656. In other word, if you set cfg.bus_type that's always authoritative unless the fwnode property contradicts it (and if that's the case, it should be documented in v4l2-fnode, unless it is and I missed it). 2.b) If the fwnode.bus_type is set, you try to parse one bus type first, if -ENOXIO try the second. If it fails again, then return an error. In the next patch, to avoid the case described in 2.a I would: - Parse the 'bus_type' property in the driver (mentioning it's for retrocompatibility). -- If not present: Assume parallel and parse the fwnode. Enclose that with a comment about "retrocompatibility" and proceed. -- If present: Do what suggested in the 2.b case. Try one, then the other, then eventually fail. I hope this makes any sense, this part is such a gray area... and as a note to "self" in the forthcoming "of_graph.yaml", let's make bus_type mandatory for all endpoints! Also, I might be mistaken in following the code and if you have tested all cases and they work as intended please call me out on this :) Thanks j > + priv->bus_type = V4L2_MBUS_PARALLEL; > + dev_notice(&client->dev, "Falling back to V4L2_MBUS_PARALLEL mode\n"); > + } > + > ret = ov772x_video_probe(priv); > if (ret < 0) > goto error_gpio_put; > -- > 2.17.1 >
Hi Sakari, THank you for the review. On Mon, Sep 14, 2020 at 7:54 AM Sakari Ailus <sakari.ailus@linux.intel.com> wrote: > > Hi Prabhakar, > > Thanks for the patchset. > > On Sun, Sep 13, 2020 at 07:42:45PM +0100, Lad Prabhakar wrote: > > Parse endpoint properties using v4l2_fwnode_endpoint_alloc_parse() > > to determine bus-type and store it locally in priv data. > > > > Also for backward compatibility with the existing DT where bus-type > > isnt specified fallback to V4L2_MBUS_PARALLEL. > > > > Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com> > > --- > > drivers/media/i2c/ov772x.c | 24 ++++++++++++++++++++++++ > > 1 file changed, 24 insertions(+) > > > > diff --git a/drivers/media/i2c/ov772x.c b/drivers/media/i2c/ov772x.c > > index 2cc6a678069a..551082aa7026 100644 > > --- a/drivers/media/i2c/ov772x.c > > +++ b/drivers/media/i2c/ov772x.c > > @@ -31,6 +31,7 @@ > > #include <media/v4l2-ctrls.h> > > #include <media/v4l2-device.h> > > #include <media/v4l2-event.h> > > +#include <media/v4l2-fwnode.h> > > #include <media/v4l2-image-sizes.h> > > #include <media/v4l2-subdev.h> > > > > @@ -434,6 +435,7 @@ struct ov772x_priv { > > #ifdef CONFIG_MEDIA_CONTROLLER > > struct media_pad pad; > > #endif > > + enum v4l2_mbus_type bus_type; > > }; > > > > /* > > @@ -1354,6 +1356,8 @@ static const struct v4l2_subdev_ops ov772x_subdev_ops = { > > > > static int ov772x_probe(struct i2c_client *client) > > { > > + struct v4l2_fwnode_endpoint bus_cfg = { .bus_type = 0 }; > > + struct fwnode_handle *ep; > > struct ov772x_priv *priv; > > int ret; > > static const struct regmap_config ov772x_regmap_config = { > > @@ -1415,6 +1419,26 @@ static int ov772x_probe(struct i2c_client *client) > > goto error_clk_put; > > } > > > > + ep = fwnode_graph_get_next_endpoint(dev_fwnode(&client->dev), > > + NULL); > > + if (!ep) { > > + dev_err(&client->dev, "endpoint node not found\n"); > > + ret = -EINVAL; > > + goto error_clk_put; > > + } > > + > > + bus_cfg.bus_type = V4L2_MBUS_PARALLEL; > > + ret = v4l2_fwnode_endpoint_alloc_parse(ep, &bus_cfg); > > + priv->bus_type = bus_cfg.bus_type; > > + v4l2_fwnode_endpoint_free(&bus_cfg); > > + if (ret) { > > + /* For backward compatibility with the existing DT where > > + * bus-type isnt specified fallback to V4L2_MBUS_PARALLEL > > "isn't", "fall back", and a period, please. > Will fix that. > > + */ > > + priv->bus_type = V4L2_MBUS_PARALLEL; > > + dev_notice(&client->dev, "Falling back to V4L2_MBUS_PARALLEL mode\n"); > > I'd just use dev_dbg(). > OK will switch to dev_dbg() Cheers, Prabhakar