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SubjectRE: [PATCH v4 2/2] misc: Add iop driver for Sunplus SP7021
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Dear Gregkh:

> > +
> > +static ssize_t sp_iop_state1_show(struct device *dev, struct
> > +device_attribute *attr, char *buf) {
> > + struct sp_iop *iop = dev_get_drvdata(dev);
> > + ssize_t len = 0;
> > +
> > + sp_iop_standby_mode(iop);
> > + mdelay(10);
> > + sp_iop_s1mode(dev, iop);
> > + return len;
> > +}
>
> This function is not showing anything.
>

The purpose of this function:
SP7021 has three power states:S0, S1 and S3.
S0:Default domain is on. IOP domain is on. AO domain is on.
S1:Default domain is off. IOP domain is on. AO domain is on.
S3:Default domain is off. IOP domain is off. AO domain is on.
System enter S1 mode when read sysfs sp_iop_state1,

I hope to provide users with the ability to enter S1 mode by themselves.
So I cannot use DEVICE_ATTR. I should use file_operations method.

> > +
> > +static ssize_t sp_iop_state1_store(struct device *dev, struct
> device_attribute *attr,
> > + const char *buf, size_t count) {
> > + ssize_t len = 0;
> > +
> > + return len;
> > +}
>
> Why do you have an empty store function?
>
> > +
> > +static ssize_t sp_iop_mode_show(struct device *dev, struct
> > +device_attribute *attr, char *buf) {
> > + struct sp_iop *iop = dev_get_drvdata(dev);
> > + ssize_t len = 0;
> > +
> > + if (iop->mode == 0)
> > + dev_info(dev, "iop_normal_mode\n");
> > + else if (iop->mode == 1)
> > + dev_info(dev, "iop_standby_mode\n");
> > + return len;
> > +}
>
> Again, this is not returning anything in sysfs.
>
> How was this tested???
>

I type "echo 0 > mode". Device driver will load normal .bin for 8051 in sp_iop_mode_store().
I type "echo 1 > mode". Device driver will load standby.bin for 8051 in sp_iop_mode_store().
I type "cat mode". I can know whether the current bin code is normal or standby in 8051.

I hope to provide users with the ability to switch bin files by themselves.
So I need to use file_operations to achieve my goal.
Not using DEVICE_ATTR. Right?


> > +static ssize_t sp_iop_mode_store(struct device *dev, struct device_attribute
> *attr,
> > + const char *buf, size_t count) {
> > + struct sp_iop *iop = dev_get_drvdata(dev);
> > + unsigned char ret = count;
> > +
> > + if (buf[0] == '0') {
> > + sp_iop_normal_mode(iop);
> > + dev_info(dev, "Switch to normal mode.\n");
> > + } else if (buf[0] == '1') {
> > + sp_iop_standby_mode(iop);
> > + dev_info(dev, "Switch to standby mode.\n");
> > + } else {
> > + dev_info(dev, "echo 0 or 1 mode\n");
> > + dev_info(dev, "0:normal mode\n");
> > + dev_info(dev, "1:standby mode\n");
> > + }
> > + return ret;
> > +}
>
> dev_info() is NOT for stuff like this at all. You do not display a "help" file or
> anything else like that in this way.
>
> Please use sysfs correctly.
>
> Also, there is a function to read 1/0 from sysfs, please use that.
>
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