Hi Aswath, On 4/6/21 5:26 PM, Aswath Govindraju wrote: > Hi Jaehoon, > > On 06/04/21 10:50 am, Aswath Govindraju wrote: >> Hi Jaehoon, >> >> On 06/04/21 3:48 am, Jaehoon Chung wrote: >>> Hi, >>> >>> On 4/5/21 11:44 PM, Aswath Govindraju wrote: >>>> From: Faiz Abbas <[email protected]> >>>> >>>> Enable HS400 speed mode by writing to HOST_CONTROL2 register. >>> >>> I didn't find HS400 bit at HOST_CONTROL2 register. (I have checked SD >>> Specific v4.20) >>> If I missed something, let me know, plz. >>> >>> In include/sdhci.h, it mentioned to "Non-standard". >>> >> >> Thank you for pointing this out. >> >> Yes, this is not a part of SD specification and in the specification >> this field is marked as reserved. I have added this, as this bit mask >> has been defined in include/sdhci.h. Sorry about this. I'll post a >> respin taking this into a consideration. >> > > On the other hand, the same has been accepted in kernel i.e. setting > SDHCI_CTRL_HS400 bit in HOST_CONTROL2 register, drivers/mmc/host/sdhci.c > in sdhci_set_uhs_signaling(). I think although this bit has not been > mentioned in the specification, it seems it is used by many controllers > for HS400 mode. So, as this is not specific to a controller can setting > this, be allowed in the common sdhci_set_uhs_timing() function ?
Frankly, i think that it can be used. Just I wondered that i missed something from Specification. :) Thanks for sharing information. I didn't check on kernel side. Best Regards, Jaehoon Chung > > Thanks, > Aswath > >> Thanks, >> Aswath >> >>> Best Regards, >>> Jaehoon Chung >>> >>>> >>>> Signed-off-by: Faiz Abbas <[email protected]> >>>> Signed-off-by: Aswath Govindraju <[email protected]> >>>> --- >>>> drivers/mmc/sdhci.c | 3 +++ >>>> 1 file changed, 3 insertions(+) >>>> >>>> diff --git a/drivers/mmc/sdhci.c b/drivers/mmc/sdhci.c >>>> index d9ab6a0a839e..eea4701d8af5 100644 >>>> --- a/drivers/mmc/sdhci.c >>>> +++ b/drivers/mmc/sdhci.c >>>> @@ -507,6 +507,9 @@ void sdhci_set_uhs_timing(struct sdhci_host *host) >>>> case MMC_HS_200: >>>> reg |= SDHCI_CTRL_UHS_SDR104; >>>> break; >>>> + case MMC_HS_400: >>>> + reg |= SDHCI_CTRL_HS400; >>>> + break; >>>> default: >>>> reg |= SDHCI_CTRL_UHS_SDR12; >>>> } >>>> >>> >> > >
