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Message-ID: <20151113093934.GA21068@b51421-server.ap.freescale.net>
Date: Fri, 13 Nov 2015 17:39:36 +0800
From: Haibo Chen <haibo.chen@...escale.com>
To: Lars-Peter Clausen <lars@...afoo.de>
CC: <robh+dt@...nel.org>, <pawel.moll@....com>, <mark.rutland@....com>,
<ijc+devicetree@...lion.org.uk>, <galak@...eaurora.org>,
<shawnguo@...nel.org>, <kernel@...gutronix.de>,
<linux@....linux.org.uk>, <jic23@...nel.org>, <knaack.h@....de>,
<pmeerw@...erw.net>, <devicetree@...r.kernel.org>,
<linux-kernel@...r.kernel.org>,
<linux-arm-kernel@...ts.infradead.org>, <linux-iio@...r.kernel.org>
Subject: Re: [PATCH v2 1/4] iio: adc: add IMX7D ADC driver support
On Tue, Nov 10, 2015 at 03:58:14PM +0100, Lars-Peter Clausen wrote:
> On 11/09/2015 02:28 PM, Haibo Chen wrote:
> > Freescale i.MX7D soc contains a new ADC IP. This patch add this ADC
> > driver support, and the driver only support ADC software trigger.
> >
> > Signed-off-by: Haibo Chen <haibo.chen@...escale.com>
>
> Looks pretty good, a few comments inline.
>
> [...]
> > +#include <linux/module.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/interrupt.h>
> > +#include <linux/delay.h>
> > +#include <linux/kernel.h>
> > +#include <linux/slab.h>
> > +#include <linux/io.h>
> > +#include <linux/clk.h>
> > +#include <linux/completion.h>
> > +#include <linux/of.h>
> > +#include <linux/of_irq.h>
> > +#include <linux/regulator/consumer.h>
> > +#include <linux/of_platform.h>
> > +#include <linux/err.h>
>
> I don't think you need all of these.
>
> [...]
Yes, I will remove delay.h slab.h of_irq.h and of_platform.h
> > +static void imx7d_adc_feature_config(struct imx7d_adc *info)
> > +{
> > + info->adc_feature.clk_pre_div = IMX7D_ADC_ANALOG_CLK_PRE_DIV_4;
> > + info->adc_feature.avg_num = IMX7D_ADC_AVERAGE_NUM_32;
> > + info->adc_feature.core_time_unit = 1;
> > + info->adc_feature.average_en = true;
>
> What's the plan for these? Right now they are always initialized to the same
> static value.
>
In future, we can get these values from dts file, currently we just use the static value.
>
> > +}
> [...]
> > +static int imx7d_adc_read_raw(struct iio_dev *indio_dev,
> > + struct iio_chan_spec const *chan,
> > + int *val,
> > + int *val2,
> > + long mask)
> > +{
> > + struct imx7d_adc *info = iio_priv(indio_dev);
> > +
> > + u32 channel;
> > + long ret;
> > +
> > + switch (mask) {
> > + case IIO_CHAN_INFO_RAW:
> > + mutex_lock(&indio_dev->mlock);
> > + reinit_completion(&info->completion);
> > +
> > + channel = (chan->channel) & 0x0f;
> > + info->channel = channel;
> > + imx7d_adc_channel_set(info);
>
> How about just passing channel directy adc_channel_set() instead of doing it
> implicitly through the info struct?
>
I think there is no difference, besides, using this parameter info struct can keep align with other functions.
eg. imx7d_adc_sample_set(), imx7d_adc_hw_init(), imx7d_adc_get_sample_rate(), all these functions have the same parameter.
> [...]
> > +static irqreturn_t imx7d_adc_isr(int irq, void *dev_id)
> > +{
> > + struct imx7d_adc *info = (struct imx7d_adc *)dev_id;
> > + int status;
> > +
> > + status = readl(info->regs + IMX7D_REG_ADC_INT_STATUS);
> > + if (status & IMX7D_REG_ADC_INT_STATUS_CHANNEL_INT_STATUS) {
> > + info->value = imx7d_adc_read_data(info);
> > + complete(&info->completion);
> > + }
> > + writel(0, info->regs + IMX7D_REG_ADC_INT_STATUS);
>
> Is the hardware really this broken? If the interrupt happens between reading
> the status register and clearing it here it will be missed.
>
I think interrupt can't happen between reading the status register and clearing it.
Because in function imx7d_adc_read_raw(), we call the function
imx7d_adc_channel_set(info), in this function, we config the register
REG_ADC_CH_A\B\C\D_CFG1 and REG_ADC_CH_A\B\C\D_CFG2, only when these registers
is configed, ADC start a conversion. Once the conversion complete, ADC trigger an
interrupt, and call the imx7d_adc_isr().
> > +
> > + return IRQ_HANDLED;
>
> You should only return IRQ_HANDLED if you actually handled are interrupt.
>
Here in the interrupt, we just handle the channel conversion finished flag, for
other flag, ignore them this time, Will add other flag in future.
> > +}
> [...]
> > +
> > +static int imx7d_adc_probe(struct platform_device *pdev)
> > +{
> > + struct imx7d_adc *info;
> > + struct iio_dev *indio_dev;
> > + struct resource *mem;
> > + int irq;
> > + int ret;
> > + u32 channels;
> > +
> > + indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(struct imx7d_adc));
> > + if (!indio_dev) {
> > + dev_err(&pdev->dev, "Failed allocating iio device\n");
> > + return -ENOMEM;
> > + }
> > +
> > + info = iio_priv(indio_dev);
> > + info->dev = &pdev->dev;
> > +
> > + mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > + info->regs = devm_ioremap_resource(&pdev->dev, mem);
> > + if (IS_ERR(info->regs)) {
> > + ret = PTR_ERR(info->regs);
> > + dev_err(&pdev->dev, "failed to remap adc memory: %d\n", ret);
> > + return ret;
> > + }
> > +
> > + irq = platform_get_irq(pdev, 0);
> > + if (irq < 0) {
> > + dev_err(&pdev->dev, "no irq resource?\n");
> > + return irq;
> > + }
> > +
> > + ret = devm_request_irq(info->dev, irq,
> > + imx7d_adc_isr, 0,
> > + dev_name(&pdev->dev), info);
>
> This is too early. Completion is not initialized, clocks are not enabled, etc...
>
You are right, I will move the request irq function down.
> > + if (ret < 0) {
> > + dev_err(&pdev->dev, "failed requesting irq, irq = %d\n", irq);
> > + return ret;
> > + }
> > +
> [...]
> > + ret = of_property_read_u32(pdev->dev.of_node,
>
> Extra space.
>
> > + "num-channels", &channels);
>
> What decides how many channels are in use?
>
The board decides the channel number.
In dts file, there is a line: num-channels = <4>;
> > + if (ret)
> > + channels = ARRAY_SIZE(imx7d_adc_iio_channels);
> > +
> > + indio_dev->name = dev_name(&pdev->dev);
> > + indio_dev->dev.parent = &pdev->dev;
> > + indio_dev->dev.of_node = pdev->dev.of_node;
> > + indio_dev->info = &imx7d_adc_iio_info;
> > + indio_dev->modes = INDIO_DIRECT_MODE;
> > + indio_dev->channels = imx7d_adc_iio_channels;
> > + indio_dev->num_channels = (int)channels;
>
> I don't think you need the case here.
>
Sorry, can't get your point, you mean I should not indio_dev-> ?
> >[...]
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