Re: [PATCH v5] mmc: support BKOPS feature for eMMC

[Chris Ball <cjb@laptop.org>]

Hi,

On Sat, Jan 07 2012, Dong, Chuanxiao wrote:
>> In my understanding, the EXT_CSD_BKOPS_EN should be _updated_by_ the
>> host controller to 1 at initialization time, to indicate to the
>> device, as per the spec.
>> Otherwise, the device would decide that the host doesn't support
>> software controlled BKOPS.
>
> EXT_CSD_BKOPS_EN is a onetime programmable register, which is not
> suitable for driver to touch I think. This can be updated by host
> controller, but should not happened in driver. This register can be
> configured by some platform firmware or some eMMC FW from vendor. For
> what driver needs to do, is just to read this onetime programmable and
> to know whether BKOPS is enabled. It is like hardware reset
> feature. RST_n_FUNCTION is only a onetime programmable register which
> can indicate whether hardware reset feature is enabled. Driver just
> needs to read it out and to know whether hardware reset feature can be
> used. So I agree with Jaehoon Chung's implementation.

I agree -- we don't touch fuses in the driver.

Thanks,

- Chris.
-- 
Chris Ball   <cjb@laptop.org>   <http://printf.net/>
One Laptop Per Child