Messages in this thread | | | Date | Tue, 1 Mar 2022 12:38:17 +0000 | Subject | Re: [PATCH] mmc: host: dw-mmc-rockchip: avoid logspam when cd-broken | From | Robin Murphy <> |
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On 2022-03-01 11:49, Peter Geis wrote: > On Tue, Mar 1, 2022 at 6:23 AM Robin Murphy <robin.murphy@arm.com> wrote: >> >> On 2022-02-28 22:36, Peter Geis wrote: >>> The dw_mmc-rockchip driver drops a large amound of logspam constantly >>> when the cd-broken flag is enabled. >>> Set the warning to be debug ratelimited in this case. >> >> Isn't this just papering over some fundamental problem with the clock? >> If it's failing to set the expected rate for communicating with a card, >> then presumably that's an issue for correct operation in general? The >> fact that polling for a card makes a lot more of that communication >> happen seems unrelated :/ > > Good Morning, > > This only happens when a card is not inserted, so communication cannot happen.
Well, I suppose there's a philosophical question in there about whether shouting into the void counts as "communication", but AFAIR what the polling function does is power up the controller, send a command, and see if it gets a response.
If the clock can't be set to the proper rate for low-speed discovery, some or all cards may not be detected properly. Conversely if it is already at a slow enough rate for discovery but can't be set higher once a proper communication mode has been established, data transfer performance will be terrible. Either way, it is not OK in general for clk_set_rate() to fail, hence the warning. You have a clock driver problem.
Cheers, Robin.
> I found it while lighting off the SoQuartz module. > As it is pin compatible with the RPi CM4, and the CM4 does not have a > card detect line, sdmmc is non functional without cd-broken. > This led to the fun spew when there wasn't a card inserted as this > function is called every poll tick. > > Thanks, > Peter > >> >> Robin. >> >>> Signed-off-by: Peter Geis <pgwipeout@gmail.com> >>> --- >>> drivers/mmc/host/dw_mmc-rockchip.c | 9 +++++++-- >>> 1 file changed, 7 insertions(+), 2 deletions(-) >>> >>> diff --git a/drivers/mmc/host/dw_mmc-rockchip.c b/drivers/mmc/host/dw_mmc-rockchip.c >>> index 95d0ec0f5f3a..d0ebf0afa42a 100644 >>> --- a/drivers/mmc/host/dw_mmc-rockchip.c >>> +++ b/drivers/mmc/host/dw_mmc-rockchip.c >>> @@ -50,8 +50,13 @@ static void dw_mci_rk3288_set_ios(struct dw_mci *host, struct mmc_ios *ios) >>> cclkin = ios->clock * RK3288_CLKGEN_DIV; >>> >>> ret = clk_set_rate(host->ciu_clk, cclkin); >>> - if (ret) >>> - dev_warn(host->dev, "failed to set rate %uHz\n", ios->clock); >>> + if (ret) { >>> + /* this screams when card detection is broken */ >>> + if (host->slot->mmc->caps & MMC_CAP_NEEDS_POLL) >>> + dev_dbg_ratelimited(host->dev, "failed to set rate %uHz\n", ios->clock); >>> + else >>> + dev_warn(host->dev, "failed to set rate %uHz\n", ios->clock); >>> + } >>> >>> bus_hz = clk_get_rate(host->ciu_clk) / RK3288_CLKGEN_DIV; >>> if (bus_hz != host->bus_hz) {
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