On 10 March 2015 at 15:32, Alex Lemberg <Alex.Lemberg@xxxxxxxxxxx> wrote: > Hi Ulf, > > Thanks for your review and comments! > >> -----Original Message----- >> From: Ulf Hansson [mailto:ulf.hansson@xxxxxxxxxx] >> Sent: Tuesday, March 10, 2015 5:08 AM >> To: Avi Shchislowski >> Cc: linux-mmc; Chris Ball; Alex Lemberg >> Subject: Re: [PATCH] mmc: sleep notification >> >> On 10 March 2015 at 10:36, Avi Shchislowski <avi.shchislowski@xxxxxxxxxxx> >> wrote: >> > This patch is implements the new additional state of >> > Power_Off_Notification – SLEEP_NOTIFICATION. >> > Until now, the implementation of Power_Off_Notification supported only >> > three modes – POWERED_ON (0x01), POWER_OFF_SHORT (0x02) and >> > POWER_OFF_LONG (0x03). >> > >> > As part of eMMC5.0 before moving to Sleep state hosts may set the >> > POWER_OFF_NOTIFICATION byte to SLEEP_NOTIFICATION (0x04). >> > After setting SLEEP_NOTIFICATION, host should wait for the busy line >> > to be de-asserted. >> > The max timeout allowed for busy line de-assertion defined in >> > SLEEP_NOTIFICATION_TIME byte in EXT_CSD [216]. >> > HPI may interrupt the SLEEP_NOTIFICATION operation. >> > In that case POWER_OFF_NOTIFICATION byte will restore to POWERED_ON. >> >> Oh, just great! JEDEC has invented yet another way of how to send a device to >> sleep state. I wonder what was wrong with the CMD5 option. > > I think before adding sleep_notification, host has no way to notify device before sending > sleep command. Now device can better prepare itself for moving into the sleep state. > > Also, I think we need to clarify one more point for this patch: > As was mentioned in commit message - Sleep_Notification can be interrupted by HPI. > This allows not blocking the host during the Sleep_Notification busy time and allows accepting > requests coming during this stage. Thus, without having HPI supported, suspend/resume process > might be influenced by Sleep_Notification busy time, and this should not happen - suspend/resume > should be done in very fast and not blocking manner. I fail to understand your comment here. Please tell me at what point(s) your think it make sense to issue the SLEEP_NOTIFICATION? If that is during the suspend phase, then a HPI request can't be triggered. Kind regards Uffe -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
