Hello, Yes, that bit only exists on Haswell. On Haswell, sample_c operations were processed at 1 pixel/clock unless you set that bit, in which case they get processed at 4 pixels/clock. The downside is that it breaks some obscure media feature that apparently no one used. Broadwell and later alway process sample_c operations at the fast speed, and there is no bit to control it. I would say that downstream patch is incorrect. --Ken On Tuesday, May 4, 2021 4:07:14 PM PDT André Almeida wrote: > Hi there, > > While browsing an old downstream kernel, I found a patch[0] that enables > sample_c optimizations at Broadwell GPUs. The message from the upstream > commit that enables it for Haswell[1] (and presumably where the code > at[0] was copied from) states that "[..] later platforms remove this > bit, and apparently always enable the optimization". > > Could you confirm that Broadwell and following architectures enable this > optimization by default (and thus, patch[0] is a no-op), or should I > upstream it? > > Thanks, > André > > [0] > https://github.com/ValveSoftware/steamos_kernel/commit/198990f13e1d9429864c177d9441a6559771c5e2 > > [1] > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=944115934436b1ff6cf773a9e9123858ea9ef3da >
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