From mboxrd@z Thu Jan 1 00:00:00 1970 From: Heiko Stuebner Subject: Re: [PATCH v3 2/2] mmc: dw_mmc: add resets support to dw_mmc Date: Fri, 01 Apr 2016 20:42 +0200 Message-ID: <1754831.FONmYVUinF@phil> References: <1459322696-29919-1-git-send-email-guodong.xu@linaro.org> <1459322696-29919-3-git-send-email-guodong.xu@linaro.org> <56FBBB2F.5030308@samsung.com> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <56FBBB2F.5030308@samsung.com> Sender: linux-kernel-owner@vger.kernel.org To: Jaehoon Chung Cc: Guodong Xu , shawn.lin@rock-chips.com, "robh+dt@kernel.org" , pawel.moll@arm.com, mark.rutland@arm.com, ijc+devicetree@hellion.org.uk, galak@codeaurora.org, ulf.hansson@linaro.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Xinwei Kong , Zhangfei Gao , "linux-mmc@vger.kernel.org" List-Id: devicetree@vger.kernel.org Am Mittwoch, 30. M=E4rz 2016, 20:40:31 schrieb Jaehoon Chung: > modified Rob's mail address. >=20 > On 03/30/2016 04:24 PM, Guodong Xu wrote: > > mmc registers may in abnormal state if mmc is used in bootloader, > > eg. to support booting from eMMC. So we need reset mmc registers > > when kernel boots up, instead of assuming mmc is in clean state. >=20 > Do you mean mmc(card side) register or dwmmc host controller's regist= er on > host side? >=20 > According to dwmmc controller TMR, there are two reset signals. One i= s > reset_n, other is rst_n. It seems this patch is relevant to reset_n(F= or > host). (rst_n is hardware reset for card.) >=20 > So could you clarify better? Then it's helpful to me for understandin= g.. I think that actually means a reset of controller IP block logic, outsi= de=20 the control of the dw_mmc block itself. On Rockchip SoCs this gets triggered from the CRU (clock and reset unit= ), so=20 I guess if I'm reading the manual correctly, should be the reset_n sign= al of=20 the ip block. rst_n on the other hand gets triggered through a dw_mmc register settin= g and=20 is already handled by the dw_mmc driver. Heiko