On Mon, Jun 10, 2024 at 02:43:17PM -0500, Sam Protsenko wrote: > On Tue, May 14, 2024 at 3:26 PM Sam Protsenko > <semen.protse...@linaro.org> wrote: > > > > On Wed, May 1, 2024 at 4:12 PM Sam Protsenko <semen.protse...@linaro.org> > > wrote: > > > > > > On Wed, Apr 10, 2024 at 9:53 PM Sean Anderson <sean...@gmail.com> wrote: > > > > > > > > On 3/7/24 19:04, Sam Protsenko wrote: > > > > > Sometimes clocks provided to a consumer might not have .set_rate > > > > > operation (like gate or mux clocks), but have CLK_SET_PARENT_RATE flag > > > > > set. In that case it's usually possible to find a parent up the tree > > > > > which is capable of setting the rate (div, pll, etc). Implement a > > > > > simple > > > > > lookup procedure for such cases, to traverse the clock tree until > > > > > .set_rate capable parent is found, and use that parent to actually > > > > > change the rate. The search will stop once the first .set_rate capable > > > > > clock is found, which is usually enough to handle most cases. > > > > > > > > > > Signed-off-by: Sam Protsenko <semen.protse...@linaro.org> > > > > > --- > > > > > > [snip] > > > > > > > > > > > Can you give an example of where this is needed? > > > > > > > > > > Sure. In my case it's needed for eMMC enablement on E850-96 board. > > > eMMC node in the device tree [1] is a gate clock > > > (CLK_GOUT_MMC_EMBD_SDCLKIN), so the MMC driver won't be able to change > > > its rate. But that clock actually has CLK_SET_RATE_PARENT flag set in > > > the clock driver [2]. So the right thing to do in this case (and > > > that's basically how it's done in Linux kernel too) is to traverse the > > > clock tree upwards, and try to find the parent capable to do .set_rate > > > (which is usually a divider clock), and use it to change the clock > > > rate. I'm working on exynos_dw_mmc driver [3] right now, making it use > > > CCF clocks, but I can't do that before this patch is applied. > > > > > > Grepping the U-Boot tree I can see the CLK_SET_RATE_PARENT flag is > > > also used in various IMX clock drivers and STM32MP13 clock driver. I > > > guess without this change those flags will be basically ignored. > > > > > > Thanks! > > > > > > > Hi Sean, > > > > Just wanted to check if you think my explanation above is ok and the > > patch can be applied? I'm finishing my new patch series for enabling > > MMC on E850-96, but this patch has to be applied first. > > > > Thanks! > > > > Hi Tom, > > Would it be reasonable to ask you to take care of this patch? It's > been ignored for 3 months now, but it's needed for eMMC enablement on > E850-96 board.
Any comments at this point Sean? -- Tom
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