From mboxrd@z Thu Jan 1 00:00:00 1970 From: vaibhav.hiremath@linaro.org (Vaibhav Hiremath) Date: Wed, 2 Sep 2015 17:13:57 +0530 Subject: [RFC 2/3] mmc: sdhci: add host_ops->voltage_switch callback for all other voltages In-Reply-To: <20150902162627.682cdedf@xhacker> 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> Message-ID: <55E6E0FD.7000806@linaro.org> To: linux-arm-kernel@lists.infradead.org List-Id: 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