On Tue, 11 May 2021 at 13:54, Lucas Stach <l.stach@xxxxxxxxxxxxxx> wrote: > > Hi Ulf, > > Am Dienstag, dem 11.05.2021 um 13:14 +0200 schrieb Ulf Hansson: > > + Chris Ruehl > > > > On Mon, 10 May 2021 at 21:04, Lucas Stach <l.stach@xxxxxxxxxxxxxx> wrote: > > > > > > From: Lucas Stach <dev@xxxxxxxxxx> > > > > > > On some boards the data strobe line isn't wired up, rendering HS400 > > > support broken, even if both the controller and the eMMC claim to > > > support it. Allow to disable HS400 mode via DT. > > > > Before I review the series, I just wanted to highlight that quite > > recently we got a related series posted from Chris [1]. I made some > > comments, but he hasn't replied yet. > > > > In any case, if I understood it correctly, it looks like some > > controllers may support HS400 ES, but not HS200. Could that be the > > case here as well? Or is this a different problem? > > > > > That's not the issue I'm trying to solve here. HS400 modes, whether ES > nor not, require the data strobe line to work. ES mode just defines how > this line is used. I know for a fact that the board I'm dealing with > here, just hasn't wired up this line between the SoC and the eMMC. Thus > HS400 modes fail to work, even though both controller and eMMC support > this mode. > > When HS400 is disabled, like in this series, communication falls back > to HS200 mode and works fine this way. Alright, thanks for clarifying. I will look into the series soon. Kind regards Uffe > > Regards, > Lucas > > > Kind regards > > Uffe > > > > [1] > > https://patchwork.kernel.org/project/linux-mmc/patch/20201208061839.21163-7-chris.ruehl@xxxxxxxxxxxx/ > > > > > > > > Signed-off-by: Lucas Stach <dev@xxxxxxxxxx> > > > --- > > > v2: > > > - move to core > > > - actually disable all HS400 modes > > > --- > > > drivers/mmc/core/host.c | 3 +++ > > > 1 file changed, 3 insertions(+) > > > > > > diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c > > > index 9b89a91b6b47..0e066c5f5243 100644 > > > --- a/drivers/mmc/core/host.c > > > +++ b/drivers/mmc/core/host.c > > > @@ -351,6 +351,9 @@ int mmc_of_parse(struct mmc_host *host) > > > host->caps2 |= MMC_CAP2_NO_SD; > > > if (device_property_read_bool(dev, "no-mmc")) > > > host->caps2 |= MMC_CAP2_NO_MMC; > > > + if (device_property_read_bool(dev, "no-mmc-hs400")) > > > + host->caps2 &= ~(MMC_CAP2_HS400_1_8V | MMC_CAP2_HS400_1_2V | > > > + MMC_CAP2_HS400_ES); > > > > > > /* Must be after "non-removable" check */ > > > if (device_property_read_u32(dev, "fixed-emmc-driver-type", &drv_type) == 0) { > > > -- > > > 2.31.1 > > > > >
