Hi Andre, I'm not familiar with the sample c message optimization. Probably Ken can comment. However I could check the internal spec here and I saw this bit only exists with this meaning in Haswell. For all the other platforms, including Broadwell it got re-purposed with a different meaning and a programming note: "This bit should be programmed to zero (0h) at all times." Also, I could not find any workaround documented anywhere recommending this bit to be set. So, I would not recommend to use it in any product, even downstream. Regardless the state of sample c message optimization in later platforms. Thanks, Rodrigo. On Tue, May 04, 2021 at 08:07:14PM -0300, 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 _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
