On Wed, Mar 30, 2022 at 10:21:37AM +0200, Vincent Whitchurch wrote: > On Mon, Mar 21, 2022 at 09:00:08AM +0100, Marek Szyprowski wrote: > > Right, I've played a bit with MCT on some older Exynos SoCs (ARM 32bit > > based and even Exynos5433) and it looked that none of it enabled MCT FRC > > timer in their proprietary firmware. I've even proposed a patch for this > > once ([1]), but such approach has been rejected. I think that calling > > exynos4_mct_frc_start() unconditionally won't hurt. > > Thank you for looking into this. The proposal was however not to avoid > changing when exynos4_mct_frc_start() is called, but to instead skip the > write to the Timer Enable bit of the G_TCON register if it is already > set, like in the below patch. (This is needed to avoid races when the > FRC is shared between CPUs in an AMP configuration, since TCON can be > modified for other reasons from the CPU which is using the global > comparator.) > > If I understand your comment correctly, such a change should not cause > any difference at least on the platforms you looked at since there > MCT_G_TCON_START will not have been set at startup. I needed the frc-shared property anyway to prevent registration of the clock events so I followed Krzysztof's suggestion of doing this conditionally and also clearing the resume callback.
