Re: [PATCH] mmc: core: Don't program invalid host driver type for fixed eMMC type

[Ian Ray]

On Tue, Oct 06, 2026 at 10:28:23AM +0300, Adrian Hunter wrote:
> On 01/10/2026 18:39, Ian Ray wrote:
> > On Wed, Sep 30, 2026 at 10:00:47PM +0300, Adrian Hunter wrote:
> >> On 29/09/2026 16:06, Ulf Hansson wrote:
> >>> + Adrian
> >>>
> >>> On Sat, Sep 26, 2026 at 2:29 PM Ian Ray <ian.ray@xxxxxxxxxxxxxxxx> wrote:
> >>>>
> >>>> The host controller driver type value used by the MMC core [1] _mostly_
> >>>> overlaps with the eMMC device I/O driver strength value [2] as shown in
> >>>> the table below; however, there is _no_ host mapping for eMMC value 4.
[...]
> >
> > The "invalid driver type" warning that I originally observed originates
> > in sdhci_set_ios_common() which is shared by all SDHCI hosts (IIUC).
> >
> > Thus any SDHCI host configured with `fixed-emmc-driver-type = <4>` would
> > log that warning.
> 
> The warning is valid.  SDHCI does not support value 4 and doesn't know
> what is a valid alternative or even if there is one.  That is up to the
> driver to sort out.  If other drivers do it the same way, then a
> helper or something could be added.
[...]
> The objective is not to avoid the warning.  The warning is valid.  The
> objective is to provide a valid value.  4 is not.
 
Thank you, I will send a v2 in which sdhci_esdhc_imx_set_ios implements
a bounds check against MMC_SET_DRIVER_TYPE_D.