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

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

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.

Cheers,
Ahmad

> 
> Sascha
> 


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