Re: [PATCH] mci: core: add device parameter for eMMC boot ack

[Sascha Hauer <s.hauer@pengutronix.de>]

On Fri, May 20, 2022 at 06:34:43AM +0200, Ahmad Fatoum wrote:
> Hello Sascha,
> 
> On 18.05.20 09:08, Sascha Hauer wrote:
> > On Wed, May 13, 2020 at 01:46:36PM +0200, Lucas Stach wrote:
> >> This adds an easy way to enable the boot acknowledge function of
> >> a eMMC device, without the need to frob the EXT_CSD setting via
> >> the mmc_extcsd command.
> >> A boot ack is required whenever the boot partitions are read via
> >> the fast initialization boot protocol.
> >>
> >> Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
> >> ---
> >>  drivers/mci/mci-core.c | 33 +++++++++++++++++++++++++++------
> >>  include/mci.h          |  2 ++
> >>  2 files changed, 29 insertions(+), 6 deletions(-)
> >>
> >> diff --git a/drivers/mci/mci-core.c b/drivers/mci/mci-core.c
> >> index f3718327f18d..d33bc0c1a41e 100644
> >> --- a/drivers/mci/mci-core.c
> >> +++ b/drivers/mci/mci-core.c
> >> @@ -516,6 +516,7 @@ static int mmc_change_freq(struct mci *mci)
> >>  
> >>  		mci->ext_csd_part_config = mci->ext_csd[EXT_CSD_PARTITION_CONFIG];
> >>  		mci->bootpart = (mci->ext_csd_part_config >> 3) & 0x7;
> >> +		mci->boot_ack_enable = (mci->ext_csd_part_config >> 6) & 0x1;
> >>  	}
> >>  
> >>  	return 0;
> >> @@ -1592,6 +1593,17 @@ static int mci_set_boot(struct param_d *param, void *priv)
> >>  			  EXT_CSD_PARTITION_CONFIG, mci->ext_csd_part_config);
> >>  }
> >>  
> >> +static int mci_set_boot_ack(struct param_d *param, void *priv)
> >> +{
> >> +	struct mci *mci = priv;
> >> +
> >> +	mci->ext_csd_part_config &= ~(0x1 << 6);
> >> +	mci->ext_csd_part_config |= mci->boot_ack_enable << 6;
> >> +
> >> +	return mci_switch(mci,
> >> +			  EXT_CSD_PARTITION_CONFIG, mci->ext_csd_part_config);
> >> +}
> > 
> > There's only one correct setting for each board or SoC. Instead of
> > letting the user choose between right and wrong, can't we add a hook to
> > be called from the board/SoC code? A device tree property might be an
> > option as well, something like barebox,enable-boot-ack.
> > 
> > There are also bits to change the bus width after power up which might
> > need adjustments which would mean another parameter with the current
> > approach.
> 
> There hasn't been any progress here for 2 years. Sascha, can we just
> take this patch? Even if we add code in future to have this happen as
> part of eMMC/SoC init, a device parameter to easily check
> the current configuration would still be useful.

Ok then, let's go for it.

Sascha

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