On Wed, 2021-03-03 at 16:20 +0100, Benjamin Gaignard wrote: > Le 03/03/2021 à 15:17, Philipp Zabel a écrit : > > Hi Benjamin, > > > > On Mon, 2021-03-01 at 16:17 +0100, Benjamin Gaignard wrote: > > > The two VPUs inside IMX8MQ share the same control block which can be see > > > as a reset hardware block. > > This isn't a reset controller though. The control block also contains > > clock gates of some sort and a filter register for the featureset fuses. > > Those shouldn't be manipulated via the reset API. > > They are all part of the control block and of the reset process for this > hardware that why I put them here. I guess it is border line :-) I'm pushing back to keep the reset control framework focused on controlling reset lines. Every side effect (such as the asymmetric clock ungating) in a random driver makes it harder to reason about behaviour at the API level, and to review patches for hardware I am not familiar with. > > > In order to be able to add the second VPU (for HECV decoding) it will be > > > more handy if the both VPU drivers instance don't have to share the > > > control block registers. This lead to implement it as an independ reset > > > driver and to change the VPU driver to use it. > > Why not switch to a syscon regmap for the control block? That should > > also allow to keep backwards compatibility with the old binding with > > minimal effort. > > I will give a try in this direction. Thank you. > > > Please note that this series break the compatibility between the DTB and > > > kernel. This break is limited to IMX8MQ SoC and is done when the driver > > > is still in staging directory. > > I know in this case we are pretty sure there are no users of this > > binding except for a staging driver, but it would still be nice to keep > > support for the deprecated binding, to avoid the requirement of updating > > kernel and DT in lock-step. > > If I want to use a syscon (or a reset) the driver must not ioremap the "ctrl" > registers. It means that "ctrl" has to be removed from the driver requested > reg-names (imx8mq_reg_names[]). Doing that break the kernel/DT compatibility. > Somehow syscon and "ctrl" are exclusive. The way the driver is set up currently, yes. You could add a bit of platform specific probe code, though, that would set up the regmap either by calling syscon_regmap_lookup_by_phandle(); for the new binding, or, if the phandle is not available, fall back to platform_get_resource_byname(..., "ctrl"); devm_ioremap_resource(); devm_regmap_init_mmio(); for the old binding. The actual codec .reset and variant .runtime_resume ops could be identical then. regards Philipp
