On Tue, Sep 15, 2015 at 09:34:15AM -0700, Rafael Antognolli wrote: > On Tue, Sep 15, 2015 at 10:35:19AM +0300, Ville Syrjälä wrote: > > On Mon, Sep 14, 2015 at 04:12:29PM -0700, Rafael Antognolli wrote: > > > This is a tentative implementation of a module that allows reading/writing > > > arbitrary dpcd registers, following the suggestion from Daniel Vetter. It > > > assumes the drm aux helpers were used by the driver. > > > > > > I tried to follow the i2c-dev implementation as close as possible, but the only > > > operations that are provided on the dev node are two different ioctl's, one for > > > reading a register and another one for writing it. > > > > Why would you use ioctls instead of normal read/write syscalls? > > > > For writing, that should work fine, I can easily change that if you > prefer. > > For reading, one has to first tell which register address is going to be > read. seek() > So it would require to first write the address on the file, to > then read. It was suggested that an ioctl to be used, and I understood > it was to solve this, but maybe I'm wrong. > > I don't have any particular preference for the API, could easily change > this code to use just read/writes. > > Thanks, > Rafael > > > > > > > I have at least 2 open questions: > > > > > > * Right now the AUX channels are stored in a global list inside the > > > drm_dp_helper implementation, and I assume that's not ideal. A different > > > approach would be to iterate over the list of connectors, instead of the > > > list of AUX channels, but that would require the struct drm_connector or > > > similar to know about the respective aux helper. It could be added as a > > > function to register that, or as a new method on the drm_connector_funcs to > > > retrieve the aux channel helper. > > > > > > * From the created sysfs drm_aux-dev device it's possible to know what is the > > > respective connector, but not the other way around. Is this good enough? > > > > > > Please provide any feedback you have and tell me if this is the idea you had > > > initially for this kind of implementation. Or, if it's nothing like this, let > > > me know what else you had in mind. > > > > > > If I'm going in the right direction, I'll refine the patch to provide full > > > documentation and tests if needed. > > > > > > Rafael Antognolli (3): > > > drm/dp: Keep a list of drm_dp_aux helper. > > > drm/dp: Store the drm_connector device pointer on the helper. > > > drm/dp: Add a drm_aux-dev module for reading/writing dpcd registers. > > > > > > Documentation/ioctl/ioctl-number.txt | 1 + > > > drivers/gpu/drm/Kconfig | 4 + > > > drivers/gpu/drm/Makefile | 1 + > > > drivers/gpu/drm/drm_aux-dev.c | 390 +++++++++++++++++++++++++++++++++++ > > > drivers/gpu/drm/drm_dp_helper.c | 71 +++++++ > > > drivers/gpu/drm/i915/intel_dp.c | 1 + > > > include/drm/drm_dp_helper.h | 7 + > > > include/uapi/linux/Kbuild | 1 + > > > include/uapi/linux/drm_aux-dev.h | 45 ++++ > > > 9 files changed, 521 insertions(+) > > > create mode 100644 drivers/gpu/drm/drm_aux-dev.c > > > create mode 100644 include/uapi/linux/drm_aux-dev.h > > > > > > -- > > > 2.4.0 > > > > > > _______________________________________________ > > > dri-devel mailing list > > > dri-devel@xxxxxxxxxxxxxxxxxxxxx > > > http://lists.freedesktop.org/mailman/listinfo/dri-devel > > > > -- > > Ville Syrjälä > > Intel OTC -- Ville Syrjälä Intel OTC _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
