Hello Thomas, On 3/30/22 12:32, Thomas Zimmermann wrote: > Hi > [snip] >>> >>> -obj-$(CONFIG_DRM_DP_HELPER) += drm_dp_helper.o >>> +obj-$(CONFIG_DRM_DISPLAY_HELPER) += drm_display_helper.o >> >> The drm_dp_helper.ko module has some parameters and this change will break >> existing kernel cmdline that are using it: >> >> $ modinfo drivers/gpu/drm/dp/drm_dp_helper.ko | grep parm | cut -d : -f2 >> drm_dp_cec_unregister_delay >> dp_aux_i2c_speed_khz >> dp_aux_i2c_transfer_size >> >> I don't know whether those are considered a kernel ABI or not though, and >> some already changed when the DP helpers were moved from drm_kms_helper.ko > > Good point. I'll mention it in the commit message andcheck the > documentation as well. > > At least, no one complained when these functions moved from kms helpers > into dp helpers. Moving them again is unfortunate, but I hope that the > new library will stick. > I was just pointing out because honestly I didn't know what was the kernel policy around changing kernel command line parameters. It seems that isn't documented anywhere. But since no one complained when these were moved from drm_kms_helper.ko and the current drm_dp_helper.ko is so recent, I would say that's fine. If you re-spin feel free to add, Reviewed-by: Javier Martinez Canillas <javierm@xxxxxxxxxx> > I somehow expected that HDMI, HDCP et al would require their own > libraries. But introducing several new and tiny kernel modules for such > small helpers wasn't worth it. Hence, there's the display library that > can collect all such helpers in a single place. > Yes, I agree with your approach to have all helpers into a single module. > It looks like MIPI DSI could be another candidate to be moved into the > display library; at least partially. I have go through the codebase to > see if there are drivers that would benefit from such a change. > Great. > Best regards > Thomas > >> > -- Best regards, Javier Martinez Canillas Linux Engineering Red Hat
