On 24 April 2017 at 11:06, Bough Chen <haibo.chen@xxxxxxx> wrote: >> -----Original Message----- >> From: Ulf Hansson [mailto:ulf.hansson@xxxxxxxxxx] >> Sent: Monday, April 24, 2017 4:12 PM >> To: Adrian Hunter <adrian.hunter@xxxxxxxxx>; Bough Chen >> <haibo.chen@xxxxxxx> >> Cc: linux-mmc@xxxxxxxxxxxxxxx; A.S. Dong <aisheng.dong@xxxxxxx> >> Subject: Re: [PATCH] mmc: debugfs: add runtime pm when cat ios or clock file >> node >> >> On 24 April 2017 at 09:16, Adrian Hunter <adrian.hunter@xxxxxxxxx> wrote: >> > On 24/04/17 10:03, Haibo Chen wrote: >> >> MMC core code add 'MMC_CAP_RUNTIME_RESUME', postpone the real >> card >> >> resume operation from bus_resume to bus_runtime_resume. So after >> >> system resume, for non-removable-card, it still not really resume. >> >> At this point, if user cat the ios or clock node, only can get zero >> >> data although the mmc/sd card is still present. >> > >> > If you ask me, getting zero is correct. >> >> I fully agree! >> >> The job for the debugfs ios node, is to report the current state, not to change it. > > Got it. > > I have one more question: take sdhci and sdhci-esdhc-imx as example, if controller in runtime suspend, then cat the ios, we will see the value including clock, but in sdhci-esdhc-imx, we already disable the usdhc clock in runtime suspend, the two are not match, I'm confused of this. Correct. The main purpose of the debugfs ios node is to provide information about the current operation conditions for the card and not really for the host. I can see it is a bit confusing, however that's how it has been a very long long time. If you need to know about current operation conditions for the host, those needs to be implemented in the host driver. Typical information could be a register dump of the controller. 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
