From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vaibhav Hiremath Subject: Re: [RFC 2/3] mmc: sdhci: add host_ops->voltage_switch callback for all other voltages Date: Wed, 2 Sep 2015 17:13:57 +0530 Message-ID: <55E6E0FD.7000806@linaro.org> References: <1441135938-8056-1-git-send-email-vaibhav.hiremath@linaro.org> <1441135938-8056-3-git-send-email-vaibhav.hiremath@linaro.org> <20150902150442.118d3305@xhacker> <55E6B129.1030002@linaro.org> <20150902162627.682cdedf@xhacker> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail-pa0-f47.google.com ([209.85.220.47]:36299 "EHLO mail-pa0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750776AbbIBLoD (ORCPT ); Wed, 2 Sep 2015 07:44:03 -0400 Received: by pacwi10 with SMTP id wi10so9194999pac.3 for ; Wed, 02 Sep 2015 04:44:02 -0700 (PDT) In-Reply-To: <20150902162627.682cdedf@xhacker> Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: Jisheng Zhang Cc: linux-mmc@vger.kernel.org, ulf.hansson@linaro.org, linus.walleij@linaro.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org On Wednesday 02 September 2015 01:56 PM, Jisheng Zhang wrote: > On Wed, 2 Sep 2015 13:49:53 +0530 > Vaibhav Hiremath wrote: > >> >> >> On Wednesday 02 September 2015 12:34 PM, Jisheng Zhang wrote: >>> On Wed, 2 Sep 2015 01:02:17 +0530 >>> Vaibhav Hiremath wrote: >>> >>>> Currently, the sdhci_do_start_signal_voltage_switch() function invokes >>>> controller specific voltage switch configuration only for 1.8v usecase; >>>> but it is required for others as well. >>>> >>>> For example, in case of PXA1928 SDH controller, we need to set different >>>> configuration for 3.3, 1.8 and 1.2 volt support (I/O domain power >>>> control register). >>>> >>>> Signed-off-by: Vaibhav Hiremath >>>> --- >>>> Note: >>>> Currently ->voltage_switch() callback is only supported >>>> in f_sdh30 driver. And I am not sure on the dependency of execution >>>> sequence for that device. I could have moved ->voltage_switch() call >>>> at one common place (above/below), but was not quite sure about it. >>>> So, replicated/duplicated the call for other voltages. >>>> >>>> drivers/mmc/host/sdhci.c | 8 ++++++++ >>>> 1 file changed, 8 insertions(+) >>>> >>>> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c >>>> index 3dd295f..b59b76d 100644 >>>> --- a/drivers/mmc/host/sdhci.c >>>> +++ b/drivers/mmc/host/sdhci.c >>>> @@ -1753,6 +1753,10 @@ static int sdhci_do_start_signal_voltage_switch(struct sdhci_host *host, >>>> /* Wait for 5ms */ >>>> usleep_range(5000, 5500); >>>> >>>> + /* Some controller need to do more when switching */ >>>> + if (host->ops->voltage_switch) >>>> + host->ops->voltage_switch(host, MMC_SIGNAL_VOLTAGE_330); >>> >>> Could this be implemented by regulator API? From patch set 3/3, the pxa1928 >>> voltage_switch hook is to operate the IO pad registers, this seems not belong >>> to the SDHC IP core. >>> >> >> Not quite sure whether regulator would be right fit for this. > > From the patche[3/3], this can be achieved by abstracting the IO PAD as regulators > then, we may not need to touch the core sdhci.c. But I'm not sure whether this > is the good solution or not. Exactly... > sdhci Maintainers and experts may have better > suggestions. > Thats is the reason I stamped it as a RFC :) Thanks, Vaibhav