Re: [PATCH v9] mmc: support BKOPS feature for eMMC

[Chris Ball <cjb@laptop.org>]

Hi,

On Fri, Jun 08 2012, Jaehoon Chung wrote:
> Enable eMMC background operations (BKOPS) feature.
>
> If URGENT_BKOPS is set after a response, note that BKOPS
> are required. After all I/O requests are finished, run
> BKOPS if required. Should read/write operations be requested
> during BKOPS, first issue HPI to interrupt the ongoing BKOPS
> and then service the request.
> If BKOPS-STATUS is upper than LEVEL2, need to check until clear
> the BKOPS-STATUS vaule. 
>
> If you want to enable this feature, set MMC_CAP2_BKOPS.
> And if you want to set the BKOPS_EN bit in ext_csd register,
> use the MMC_CAP2_INIT_BKOPS.
[..]
> diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
> index 0707d22..d23caf2 100644
> --- a/include/linux/mmc/host.h
> +++ b/include/linux/mmc/host.h
> @@ -238,6 +238,8 @@ struct mmc_host {
>  #define MMC_CAP2_BROKEN_VOLTAGE	(1 << 7)	/* Use the broken voltage */
>  #define MMC_CAP2_DETECT_ON_ERR	(1 << 8)	/* On I/O err check card removal */
>  #define MMC_CAP2_HC_ERASE_SZ	(1 << 9)	/* High-capacity erase size */
> +#define MMC_CAP2_INIT_BKOPS	(1 << 10)	/* To enable BKOPS */
> +#define MMC_CAP2_BKOPS		(1 << 11)	/* BKOPS supported */

Can we have a better explanation of how these capabilities are supposed
to be used, and why it's necessary to have two of them?  Why would you
set one but not the other?

Thanks,

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