On 15/01/2022 16:06, Alexey Sheplyakov wrote: > On a dual core group GPUs (such as T628) fragment shading can be > performed over all cores (because a fragment shader job doesn't > need coherency between threads), however vertex shading requires > to be run on the same core group as the tiler (which always lives > in core group 0). > > As a first step to support T628 power on only the first core group > (so no jobs are scheduled on the second one). This makes T628 look > like every other Midgard GPU (and throws away up to half the cores). > > With this patch panfrost is able to drive T628 (r1p0) GPU on some > armv8 SoCs (in particular BE-M1000). Without the patch rendering > is horriby broken (desktop is completely unusable) and eventually > the GPU locks up (it takes from a few seconds to a couple of > minutes). > > Using the second core group requires support in Mesa (and an UABI > change): the userspace should > > 1) set PANFROST_JD_DOESNT_NEED_COHERENCY_ON_GPU flag to opt-in > to allowing the job to run across all cores. > 2) set PANFROST_RUN_ON_SECOND_CORE_GROUP flag to allow compute > jobs to be run on the second core group (at the moment Mesa > does not advertise compute support on anything older than > Mali T760) Minor comment: these flags obviously don't exist yet, and I would prefer some more thought went into the names before we merge a new UABI. I picked overly verbose names (for the purposes of discussion) in the hope that it was 'obvious' I hadn't thought about the names, but in hindsight realise this perhaps wasn't obvious. As well as being too verbose, the second name is missing the "_JD_" part of the prefix. > > But there's little point adding such flags until someone (myself) > steps up to do the Mesa work. > > Signed-off-by: Alexey Sheplyakov <asheplyakov@xxxxxxxxxx> > Signed-off-by: Vadim V. Vlasov <vadim.vlasov@xxxxxxxxxxx> > Tested-by: Alexey Sheplyakov <asheplyakov@xxxxxxxxxx> Since I basically wrote the patch you should have included a credit here for me (see the developer certificate of origin[1]). But thank you for writing up a detailed commit message. I'll push to drm-misc-next with a Co-developed-by for me. Thanks for testing the patch and good luck with the Mesa changes! Thanks, Steve [1] https://developercertificate.org/ > --- > drivers/gpu/drm/panfrost/panfrost_gpu.c | 27 ++++++++++++++++++++----- > 1 file changed, 22 insertions(+), 5 deletions(-) > > diff --git a/drivers/gpu/drm/panfrost/panfrost_gpu.c b/drivers/gpu/drm/panfrost/panfrost_gpu.c > index f8355de6e335..15cec831a99a 100644 > --- a/drivers/gpu/drm/panfrost/panfrost_gpu.c > +++ b/drivers/gpu/drm/panfrost/panfrost_gpu.c > @@ -320,19 +320,36 @@ void panfrost_gpu_power_on(struct panfrost_device *pfdev) > { > int ret; > u32 val; > + u64 core_mask = U64_MAX; > > panfrost_gpu_init_quirks(pfdev); > > - /* Just turn on everything for now */ > - gpu_write(pfdev, L2_PWRON_LO, pfdev->features.l2_present); > + if (pfdev->features.l2_present != 1) { > + /* > + * Only support one core group now. > + * ~(l2_present - 1) unsets all bits in l2_present except > + * the bottom bit. (l2_present - 2) has all the bits in > + * the first core group set. AND them together to generate > + * a mask of cores in the first core group. > + */ > + core_mask = ~(pfdev->features.l2_present - 1) & > + (pfdev->features.l2_present - 2); > + dev_info_once(pfdev->dev, "using only 1st core group (%lu cores from %lu)\n", > + hweight64(core_mask), > + hweight64(pfdev->features.shader_present)); > + } > + gpu_write(pfdev, L2_PWRON_LO, pfdev->features.l2_present & core_mask); > ret = readl_relaxed_poll_timeout(pfdev->iomem + L2_READY_LO, > - val, val == pfdev->features.l2_present, 100, 20000); > + val, val == (pfdev->features.l2_present & core_mask), > + 100, 20000); > if (ret) > dev_err(pfdev->dev, "error powering up gpu L2"); > > - gpu_write(pfdev, SHADER_PWRON_LO, pfdev->features.shader_present); > + gpu_write(pfdev, SHADER_PWRON_LO, > + pfdev->features.shader_present & core_mask); > ret = readl_relaxed_poll_timeout(pfdev->iomem + SHADER_READY_LO, > - val, val == pfdev->features.shader_present, 100, 20000); > + val, val == (pfdev->features.shader_present & core_mask), > + 100, 20000); > if (ret) > dev_err(pfdev->dev, "error powering up gpu shader"); > >
