Re: [PATCH v2] mmc: Avoid reprogram all keys to Inline Crypto Engine for MMC runtime suspend resume

[Eric Biggers <ebiggers@kernel.org>]

On Fri, Jun 06, 2025 at 04:17:14PM +0530, Debraj Mukhopadhyay wrote:
> Crypto reprogram all keys is called for each MMC runtime
> suspend/resume in current upstream design.

It's called from mmc_set_initial_state(), which is documented as:

/*
 * Set initial state after a power cycle or a hw_reset.
 */

Please clarify how that corresponds to "MMC runtime suspend/resume".

> streaming applications have been observed due to this. Add the flag
> MMC_CAP2_DONT_REPROGRAM as part of host->caps2 to control reprogramming
> keys to crypto engine for socs which dont require this feature.

The flag has a different name in the code.

> diff --git a/drivers/mmc/core/crypto.c b/drivers/mmc/core/crypto.c
> index fec4fbf16a5b..d41672e2856e 100644
> --- a/drivers/mmc/core/crypto.c
> +++ b/drivers/mmc/core/crypto.c
> @@ -15,7 +15,7 @@
>  void mmc_crypto_set_initial_state(struct mmc_host *host)
>  {
>  	/* Reset might clear all keys, so reprogram all the keys. */
> -	if (host->caps2 & MMC_CAP2_CRYPTO)
> +	if (host->caps2 & MMC_CAP2_CRYPTO && !(host->caps2 & MMC_CAP2_CRYPTO_NO_REPROG))
>  		blk_crypto_reprogram_all_keys(&host->crypto_profile);

Add parentheses around 'host->caps2 & MMC_CAP2_CRYPTO'

> +#ifdef CONFIG_MMC_CRYPTO
> +#define MMC_CAP2_CRYPTO_NO_REPROG	(1 << 29)	/* Host does not support inline crypto key reprogramming */
> +#else
> +#define MMC_CAP2_CRYPTO_NO_REPROG	0
> +#endif

Well, it does support inline crypto key reprogramming.  It just doesn't want the
MMC core driver to handle it.  Please update the comment to something like:
/* Host driver handles crypto key reprogramming */

- Eric