On June 6, 2019 11:37:22 PM Doug Anderson <dianders@xxxxxxxxxxxx> wrote:
In the case of dw_mmc, which I'm most familiar with, we don't have any sort of automated or timed-based retuning. ...so we'll only re-tune when we see the CRC error. If I'm understanding things correctly then that for dw_mmc my solution and yours behave the same. That means the difference is how we deal with other retuning requests, either ones that come about because of an interrupt that the host controller provided or because of a timer. Did I get that right?
Right.
...and I guess the reason we have to deal specially with these cases is because any time that SDIO card is "sleeping" we don't want to retune because it won't work. Right? NOTE: the solution that would come to my mind first to solve this would be to hold the retuning for the whole time that the card was sleeping and then release it once the card was awake again. ...but I guess we don't truly need to do that because tuning only happens as a side effect of sending a command to the card and the only command we send to the card is the "wake up" command. That's why your solution to hold tuning while sending the "wake up" command works, right?
Yup.
--- OK, so assuming all the above is correct, I feel like we're actually solving two problems and in fact I believe we actually need both our approaches to solve everything correctly. With just your patch in place there's a problem because we will clobber any external retuning requests that happened while we were waking up the card. AKA, imagine this: A) brcmf_sdio_kso_control(on=True) gets called; need_retune starts as 0 B) We call sdio_retune_hold_now() C) A retuning timer goes off or the SD Host controller tells us to retune D) We get to the end of brcmf_sdio_kso_control() and clear the "retune needed" since need_retune was 0 at the start. ...so we dropped the retuning request from C), right? What we truly need is: 1. CRC errors shouldn't trigger a retuning request when we're in brcmf_sdio_kso_control() 2. A separate patch that holds any retuning requests while the SDIO card is off. This patch _shouldn't_ do any clearing of retuning requests, just defer them. Does that make sense to you? If so, I can try to code it up...
FWIW it does make sense to me. However, I am still not sure if our sdio hardware supports retuning. Have to track down an asic designer who can tell or dive into vhdl myself.
So I want to disable device sleep and trigger retuning through debugfs or some other hack.
Regards, Arend _______________________________________________ Linux-rockchip mailing list Linux-rockchip@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/linux-rockchip
