Hi Hans, Sakari and Luca On Tue, Aug 28, 2018 at 11:22:28AM +0200, Hans Verkuil wrote: > On 26/08/18 22:41, Luca Ceresoli wrote: > > Hi Sakari, > > > > On 25/08/2018 16:49, Sakari Ailus wrote: > >> Hi Luca, > >> > >> On Fri, Aug 24, 2018 at 06:35:21PM +0200, Luca Ceresoli wrote: > >>> Forcibly setting the subdev name to DRIVER_NAME (i.e. "IMX274") makes > >>> it non-unique and less informative. > >>> > >>> Let the driver use the default name from i2c, e.g. "IMX274 2-001a". > >>> > >>> Signed-off-by: Luca Ceresoli <luca@xxxxxxxxxxxxxxxx> > >>> --- > >>> drivers/media/i2c/imx274.c | 1 - > >>> 1 file changed, 1 deletion(-) > >>> > >>> diff --git a/drivers/media/i2c/imx274.c b/drivers/media/i2c/imx274.c > >>> index 9b524de08470..570706695ca7 100644 > >>> --- a/drivers/media/i2c/imx274.c > >>> +++ b/drivers/media/i2c/imx274.c > >>> @@ -1885,7 +1885,6 @@ static int imx274_probe(struct i2c_client *client, > >>> imx274->client = client; > >>> sd = &imx274->sd; > >>> v4l2_i2c_subdev_init(sd, client, &imx274_subdev_ops); > >>> - strlcpy(sd->name, DRIVER_NAME, sizeof(sd->name)); > >>> sd->flags |= V4L2_SUBDEV_FL_HAS_DEVNODE | V4L2_SUBDEV_FL_HAS_EVENTS; > >>> > >>> /* initialize subdev media pad */ > >> > >> This ends up changing the entity as well as the sub-device name which may > >> well break applications. > > > > Right, unfortunately. > > > >> On the other hand, you currently can't have more > >> than one of these devices on a media device complex due to the name being > >> specific to a driver, not the device. > >> > >> An option avoiding that would be to let the user choose by e.g. through a > >> Kconfig option would avoid having to address that, but I really hate adding > >> such options. > > > > I agree adding a Kconfig option just for this would be very annoying. > > However I think the issue affects a few other drivers (sr030pc30.c and > > s5c73m3-core.c apparently), thus maybe one option could serve them all. > > > >> I wonder what others think. If anyone ever needs to add another on a board > >> so that it ends up being the part of the same media device complex > >> (likely), then changing the name now rather than later would be the least > >> pain. In this case I'd be leaning (slightly) towards accepting the patch > >> and hoping there wouldn't be any fallout... I don't see any board (DT) > >> containing imx274, at least not in the upstream kernel. > > > > I'll be OK with either decision. Should we keep it as is, then I think a > > comment before that line would be appropriate to clarify it's not > > correct but it is kept for backward userspace compatibility. This would > > help avoid new driver writers doing the same mistake, and prevent other > > people to send another patch like mine. > > In this end, this is a driver bug. I would just fix this, but add a comment > that states the old name and why it was changed. No need for a dev_info > IMHO. > > It would be nice if you can check if the same mistake is made in other drivers, > and update those as well. It's easier if this is all done at the same time. > Then we should probably also apply the following patch I submitted : "media: v4l2-common: v4l2_spi_subdev_init : generate unique name" https://patchwork.kernel.org/patch/10553035/ and perhaps "media: v4l2-common: simplify v4l2_i2c_subdev_init name generation" https://patchwork.kernel.org/patch/10553037/ Philippe -- Philippe De Muyter +32 2 6101532 Macq SA rue de l'Aeronef 2 B-1140 Bruxelles
