On Fri, Oct 23, 2020 at 3:25 AM Lucas Stach <l.stach@xxxxxxxxxxxxxx> wrote: > > On Do, 2020-10-22 at 13:31 -0500, Adam Ford wrote: > > On Thu, Oct 22, 2020 at 1:17 PM Marek Vasut <marex@xxxxxxx> wrote: > > > On 10/22/20 7:16 PM, Adam Ford wrote: > > > > According to the documentation from NXP, the i.MX8M Nano has a > > > > Vivante GC7000 Ultra Lite as its GPU core. > > > > > > > > With this patch, the Etnaviv driver presents the GPU as: > > > > etnaviv-gpu 38000000.gpu: model: GC7000, revision: 6203 > > > > > > > > It uses the GPCV2 controller to enable the power domain for the > > > > GPU. > > > > > > Subject should say 8mn , not 8mm . > > > > ugh.. My mistake. I'll submit a V2 once other have had a chance to > > give some feedback. > > > > Maybe NXP can comment on the dialog below. > > > > > Are the assigned-clock-rates correct ? > > > > I used the assigned clock rates from the vendor kernel, with the > > exception of running at 400MHz instead of 600MHz. According to the > > datasheet, the GPU clock needs to be 400MHZ to run at 0.85V. The > > 600MHz operating point for the GPU requires a 0.95V operating point. > > Since the default operating point for the Nano shows 0.85V, I left > > the > > GPU clock lower to match the normal operating speed. This varies a > > bit from the vendor kernel, but their kernel is also showing a 0.95V > > operating point, so I think that's why they are specifying a 600MHz > > operating point. > > > > On the Beacon embedded board, we're driving the LPDDR to 800MHz which > > requires the ARM to run at .95V. I was able to override the > > assigned-clock rates for my board to run at 600MHz, and change the > > ARM > > operating point to .95V to meet the spec. > > > > My intent was to use the defaults and let the board files override > > them. If you want, I can try to look through the board files to see > > what operating point their using and propose updates to those > > respective device trees to address the clocks on those boards. > > I think this is fine as-is with this explanation. At least we have a > precedent in the i.MX8MQ DT where the assigned clocks are for the base > (non overdrive) operating point and boards can choose to override it if > they want to use the overdrive OPP. At least until we add proper > frequency scaling in etnaviv, which should obsolete those fixed clock > rates. I have to do a V2 from the feedback of Krzysztof. I will expand the commit message to include the description of the 400MHz vs 600MHz clocking and the need for adjusting the operating points. adam > > Regards, > Lucas >
