From mboxrd@z Thu Jan 1 00:00:00 1970 From: Shawn Lin Subject: Re: [PATCH 2/2] mmc: dw_mmc: add resets support to dw_mci_parse_dt() Date: Fri, 4 Mar 2016 11:45:57 +0800 Message-ID: <56D904F5.9020700@rock-chips.com> References: <1456968818-22140-1-git-send-email-guodong.xu@linaro.org> <1456968818-22140-2-git-send-email-guodong.xu@linaro.org> <56D79AB4.7050809@rock-chips.com> <56D900A8.9070204@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset=gbk; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <56D900A8.9070204-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: zhangfei , Guodong Xu , robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, pawel.moll-5wv7dgnIgG8@public.gmane.org, mark.rutland-5wv7dgnIgG8@public.gmane.org, ijc+devicetree-KcIKpvwj1kUDXYZnReoRVg@public.gmane.org, galak-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org, jh80.chung-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org, ulf.hansson-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mmc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Cc: shawn.lin-TNX95d0MmH7DzftRWevZcw@public.gmane.org, shawn.lin-NgiFYW8Wbx6Ta72+1OMJgUB+6BGkLq7r@public.gmane.org, Xinwei Kong List-Id: linux-mmc@vger.kernel.org =D4=DA 2016/3/4 11:27, zhangfei =D0=B4=B5=C0: > > > On 03/03/2016 10:00 AM, Shawn Lin wrote: >> Hi Guodong, >> >> On 2016/3/3 9:33, Guodong Xu wrote: >>> With this, user can add a 'resets' property into dw_mmc dts >>> node, and when driver probe and parse_dt, it will call >>> reset APIs to reset dw_mmc host controller. >>> >>> Please also refer to Documentation/devicetree/bindings/reset/reset.= txt >> >> I have no hard objection for this patch, but I'd rather not add it >> unless we actually need it. Could you elaborate more about any futhe= r >> actions you will take if it's applied(i.e: deal with some unrecovera= ble >> broken case)? If we just reset the controller while probing, actual= ly I >> can't find any problems without it based on tons of my reboot test. > > mmc register maybe abnormal state, if mmc is used in uefi, like boot > from emmc. > So we need reset mmc register when kernel boot up, instead of assumin= g > mmc is in clean state. > Next step is adding reset node in dts for drivers/mmc/host/dw_mmc-k3.= c > as reset driver is already there. =46air enough. Thanks for explaining. > >>> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c >>> index 242f9a0..d3a7376 100644 >>> --- a/drivers/mmc/host/dw_mmc.c >>> +++ b/drivers/mmc/host/dw_mmc.c >>> @@ -2878,6 +2878,13 @@ static struct dw_mci_board >>> *dw_mci_parse_dt(struct dw_mci *host) >>> if (!pdata) >>> return ERR_PTR(-ENOMEM); >>> >>> + /* find reset controller when exist */ >>> + pdata->rstc =3D devm_reset_control_get_optional(dev, NULL); >>> + if (IS_ERR(pdata->rstc)) >>> + pdata->rstc =3D NULL; >>> + else >>> + reset_control_deassert(pdata->rstc); >>> + >> >> if the PTR_ERR(pdata->rstc) is -EPROBE_DEFER, should we defer probin= g >> the driver? > Yes, good catch. > > Thanks > > > --=20 Best Regards Shawn Lin -- To unsubscribe from this list: send the line "unsubscribe devicetree" i= n the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html