From: Lars Persson <lars.persson-VrBV9hrLPhE@public.gmane.org>
To: Arnd Bergmann <arnd-r2nGTMty4D4@public.gmane.org>,
Lars Persson <larper-VrBV9hrLPhE@public.gmane.org>
Cc: linux-mmc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
g.liakhovetski-Mmb7MZpHnFY@public.gmane.org,
ulf.hansson-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org,
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
Subject: Re: [PATCH v3 2/3] mmc: usdhi6rol0: add support for UHS modes
Date: Thu, 21 Apr 2016 10:26:55 +0200 [thread overview]
Message-ID: <57188ECF.70101@axis.com> (raw)
In-Reply-To: <4129305.Ka9B8YpEaI@wuerfel>
On 04/21/2016 09:53 AM, Arnd Bergmann wrote:
> On Thursday 21 April 2016 09:12:52 Lars Persson wrote:
>> On 04/20/2016 04:53 PM, Lars Persson wrote:
>>> Add a start_signal_voltage_switch() operation to support enabling of
>>> UHS modes.
>>>
>>> Signed-off-by: Lars Persson <larper-VrBV9hrLPhE@public.gmane.org>
>>> ---
>>> drivers/mmc/host/usdhi6rol0.c | 13 +++++++++++++
>>> 1 file changed, 13 insertions(+)
>>>
>>> diff --git a/drivers/mmc/host/usdhi6rol0.c b/drivers/mmc/host/usdhi6rol0.c
>>> index 807c06e..2585ea4 100644
>>> --- a/drivers/mmc/host/usdhi6rol0.c
>>> +++ b/drivers/mmc/host/usdhi6rol0.c
>>> @@ -1147,12 +1147,25 @@ static void usdhi6_enable_sdio_irq(struct mmc_host *mmc, int enable)
>>> }
>>> }
>>>
>>> +static int usdhi6_sig_volt_switch(struct mmc_host *mmc, struct mmc_ios *ios)
>>> +{
>>> + int ret;
>>> +
>>
>> To support boards without regulator we need to put a
>> IS_ERR_OR_NULL(mmc->supply.vqmmc) check here and bail out with return 0.
>> Missing vqmmc is OK according to our binding document, but treated as an
>> error by mmc_regulator_set_vqmmc().
>
> mmc_regulator_set_vqmmc() should already take care of handling
> all the those cases. In general, it's almost always a bug to use
> IS_ERR_OR_NULL(): if you ever feel the need to use it, you should
> either fix the code that made the pointer ambiguous or you have
> misunderstood the interface.
>
> Arnd
>
Yes it should of course be IS_ERR() rather than IS_ERR_OR_NULL().
It is a common pattern in all upstream mmc drivers to not make the call
to mmc_regulator_set_vqmmc() when a regulator is missing. We basically
want to log errors except for the EINVAL returned in case of a missing
regulator.
- Lars
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next prev parent reply other threads:[~2016-04-21 8:26 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-20 14:53 [PATCH v3 0/3] mmc: usdhi6rol0: UHS support Lars Persson
2016-04-20 14:53 ` [PATCH v3 1/3] mmc: dt: usdhi6rol0: add optional pinctrl binding Lars Persson
2016-04-20 14:53 ` [PATCH v3 2/3] mmc: usdhi6rol0: add support for UHS modes Lars Persson
2016-04-21 7:12 ` Lars Persson
2016-04-21 7:53 ` Arnd Bergmann
2016-04-21 8:26 ` Lars Persson [this message]
2016-04-21 9:52 ` Arnd Bergmann
2016-04-21 13:47 ` Lars Persson
2016-04-20 14:53 ` [PATCH v3 3/3] mmc: usdhi6rol0: add pinctrl to set pin drive strength Lars Persson
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