Re: [PATCH v3] mmc: Avoid reprogram all keys to Inline Crypto Engine for MMC runtime suspend resume

[Neeraj Soni <neeraj.soni@oss.qualcomm.com>]

Hi,

On 1/8/2026 3:13 PM, Konrad Dybcio wrote:
> On 1/6/26 7:49 AM, Neeraj Soni wrote:
>> Hi,
>>
>> Aplogies for replying so late to the queries.
>>
>> On 7/18/2025 5:35 PM, Konrad Dybcio wrote:
>>> On 7/18/25 1:02 PM, Debraj Mukhopadhyay wrote:
>>>> Crypto reprogram all keys is called for each MMC runtime
>>>> suspend/resume in current upstream design. If this is implemented
>>>> as a non-interruptible call to TEE for security, the cpu core is
>>>> blocked for execution while this call executes although the crypto
>>>> engine already has the keys. For example, glitches in audio/video
>>>> streaming applications have been observed due to this. Add the flag
>>>> MMC_CAP2_CRYPTO_NO_REPROG as part of host->caps2 to control reprogramming
>>>> keys to crypto engine for socs which dont require this feature.
>>>>
>>>> Signed-off-by: Seshu Madhavi Puppala <quic_spuppala@quicinc.com>
>>>> Co-developed-by: Ram Prakash Gupta <quic_rampraka@quicinc.com>
>>>> Signed-off-by: Ram Prakash Gupta <quic_rampraka@quicinc.com>
>>>> Co-developed-by: Sarthak Garg <quic_sartgarg@quicinc.com>
>>>> Signed-off-by: Sarthak Garg <quic_sartgarg@quicinc.com>
>>>> Signed-off-by: Debraj Mukhopadhyay <quic_dmukhopa@quicinc.com>
>>>>
>>>> ---
> 
> [...]
> 
>>>> @@ -459,6 +459,11 @@ struct mmc_host {
>>>>  #define MMC_CAP2_CRYPTO		0
>>>>  #endif
>>>>  #define MMC_CAP2_ALT_GPT_TEGRA	(1 << 28)	/* Host with eMMC that has GPT entry at a non-standard location */
>>>> +#ifdef CONFIG_MMC_CRYPTO
>>>> +#define MMC_CAP2_CRYPTO_NO_REPROG	(1 << 29)	/* Host handles inline crypto key reprogramming */
>>>> +#else
>>>> +#define MMC_CAP2_CRYPTO_NO_REPROG	0
>>>> +#endif
>>> This (and the crypto ifdef for MMC_CAP2_CRYPTO) looks like unnecessary
>>> churn - crypto functions should never be called if the config is disabled
>>> in the first place
>> Do you suggest to remove #ifdef? I am not sure why #ifdef is used with MMC_CAP2_CRYPTO
>> (may be to reuse the bits if config is not defined) but for MMC_CAP2_CRYPTO_NO_REPROG we
>> followed the approach used for MMC_CAP2_CRYPTO.
> 
> We got plenty of bits, let's not waste the time of a programmer trying
> to figure out whether his particular combination of configs is going to
> collide with the reuse, I'd argue the ifdef is unnecessary
>
Sure. I will remove the #ifdef from MMC_CAP2_CRYPTO and MMC_CAP2_CRYPTO_NO_REPROG in next patch.
 
> Konrad
> 
Regards
Neeraj