From mboxrd@z Thu Jan 1 00:00:00 1970 From: Javier Martinez Canillas Subject: Re: [PATCH v2 06/12] mmc: pwrseq: add support for power-on sequencing through DT Date: Fri, 8 Jan 2016 09:22:31 -0300 Message-ID: <568FAA07.1010509@osg.samsung.com> References: <1452155155-16232-1-git-send-email-wxt@rock-chips.com> <1452155155-16232-7-git-send-email-wxt@rock-chips.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1452155155-16232-7-git-send-email-wxt@rock-chips.com> Sender: linux-mmc-owner@vger.kernel.org To: Caesar Wang , Heiko Stuebner , Ulf Hansson Cc: linux-rockchip@lists.infradead.org, leecam@google.com, leozwang@google.com, keescook@google.com, Srinivas Kandagatla , linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org, Alexandre Courbot , NeilBrown List-Id: linux-rockchip.vger.kernel.org Hello Caesar, On 01/07/2016 05:25 AM, Caesar Wang wrote: > This patch enables support for power-on sequencing of SDIO > peripherals through DT. > I think the subject line and this first paragraph are misleading since the simple power sequence provider already supports power-on sequencing. This patch does not add or enable support but extends the current support to also enable a regulator as a part of the SDIO chip power on sequencing. > In general, it's quite common that wifi modules and other similar > peripherals have several signals in addition to the SDIO interface that > needs wiggling before the module will power on. > > For example: > we need enable wifi module power to via the WL_REG_ON > pin, we need enable it as the regulator if this pin is connected to > the gpio of cpu. > This part confuses me, so does your chip have an actual regulator that needs to be enabled or is just a fake regulator whose gpio property is used not to enable the regulator but to toggle the WL_REG_ON pin of the WiFi chip? > Maybe, someone will say that can pull up/down from dts. > Unfortunately some SoCs can't support pinctrl pull up/down in > internal. > Can you please elaborate on this? AFAIU this limitation is the reason why you went with the regulator approach so I think it deserve a more deep explanation. > Anyway, we can add this patch to supprt the power-on sequencing for s/supprt/support > sdio. > > Signed-off-by: Caesar Wang > Best regards, -- Javier Martinez Canillas Open Source Group Samsung Research America