From mboxrd@z Thu Jan  1 00:00:00 1970
From: Timur Tabi <timur@codeaurora.org>
Subject: Re: [PATCH 1/2] pinctrl: qcom: disable GPIO groups with no pins
Date: Fri, 14 Jul 2017 16:43:56 -0500
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To: Stephen Boyd <sboyd@codeaurora.org>
Cc: andy.gross@linaro.org, david.brown@linaro.org, Linus Walleij <linus.walleij@linaro.org>, Bjorn Andersson <bjorn.andersson@linaro.org>, linux-gpio@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-arm-kernel@lists.infradead.org

On 07/14/2017 12:11 PM, Stephen Boyd wrote:
> gpiochips also have a request() hook. Can we use that before
> initializing direction to make sure the GPIO is accessible?

So I tried it, and it didn't work:

static int msm_gpio_request(struct gpio_chip *chip, unsigned int offset)
{
	pr_info("%s:%u offset=%u\n", __func__, __LINE__, offset);

	return 0;
}

static struct gpio_chip msm_gpio_template = {
	.request          = msm_gpio_request,
	...

msm_gpio_request() is never called when the driver loads.  In fact, I 
can't figure out when it would be called.

-- 
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm
Technologies, Inc.  Qualcomm Technologies, Inc. is a member of the
Code Aurora Forum, a Linux Foundation Collaborative Project.