On Wed 15 Mar 2023 at 11:20, Marc Gonzalez <marc.w.gonzalez@xxxxxxx> wrote: > On 14/03/2023 20:45, Heiner Kallweit wrote: > >> On 14.03.2023 18:24, Marc Gonzalez wrote: >> >>> With the default power-up delay, on small kernels, the host probes >>> too soon, and mmc_send_io_op_cond() times out. >> >> Looking at mmc_power_up() and how power_delay_ms is used >> I wonder what you mean with "host probes too soon". > > Hello Heiner, > > Thanks for your interest in my patch! :) > > I should have added a link to the thread that led to the patch. > https://patchwork.kernel.org/project/linux-wireless/patch/c1a215cf-94be-871b-2a8a-3cc381588f83@xxxxxxx/ > Start at "I have run into another issue." > > Basically, I have an S905X2-based board. > I built a small kernel for it (with only a few drivers), that boots really fast. > > mmc2 (SDIO controller hooked to WiFi chip) would not probe at all, > unless I added lots of printks. > Basically, calling mmc_send_io_op_cond() too soon after the controller > has been reset leads to the CMD5 request timing out. > > I tend to agree with Heiner here. This patch is backing a contraint only reported on your design in the driver of every AML SoC supported, for every MMC controller. I think you should look first in your vmmc and vqmmc regulators and their setup times. "fixed-regulator" have properties which might be interesting to you, like * startup-delay-us * off-on-delay-us >> Are you sure that the additional delay is needed for the Amlogic MMC >> block IP in general? Or could it be that your issue is caused by >> a specific regulator and you need to add a delay there? > > The eternal question... > > I have only one type of board. (Actually, I have a reference design > that is slightly different, so I should test on that one as well.) > > In vendor kernels, they add delays to the WiFi drivers. > Maybe they have run into the issue, and they're just fixing the symptom? > > Default value for ios.power_delay_ms is 10 ms. > msleep(ios.power_delay_ms) is called twice in mmc_power_up(). > So raising the delay from 10 to 20 adds 20 ms > to the latency of initializing SDIO/SD/MMC controllers. > > Would you be willing to test if the problem manifests on your board? > > Regards
