linux-kernel - Re: [PATCH v4 1/5] mfd: Add support for Intel LJCA device

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Date:   Thu, 9 Mar 2023 10:41:05 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     "Ye, Xiang" <xiang.ye@...el.com>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Matthias Kaehlcke <mka@...omium.org>,
        Lee Jones <lee@...nel.org>, Wolfram Sang <wsa@...nel.org>,
        Tyrone Ting <kfting@...oton.com>,
        Mark Brown <broonie@...nel.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <brgl@...ev.pl>, linux-usb@...r.kernel.org,
        linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-spi@...r.kernel.org, linux-gpio@...r.kernel.org,
        srinivas.pandruvada@...el.com, heikki.krogerus@...ux.intel.com,
        andriy.shevchenko@...ux.intel.com, sakari.ailus@...ux.intel.com,
        zhifeng.wang@...el.com, wentong.wu@...el.com, lixu.zhang@...el.com
Subject: Re: [PATCH v4 1/5] mfd: Add support for Intel LJCA device

On Thu, Mar 09, 2023 at 05:31:44PM +0800, Ye, Xiang wrote:
> On Thu, Mar 09, 2023 at 08:52:24AM +0100, Greg Kroah-Hartman wrote:
> > On Thu, Mar 09, 2023 at 03:10:56PM +0800, Ye Xiang wrote:
> > > +static int ljca_mng_get_version(struct ljca_stub *stub, char *buf)
> > > +{
> > > +	struct fw_version version = {};
> > > +	unsigned int len = sizeof(version);
> > > +	int ret;
> > > +
> > > +	ret = ljca_stub_write(stub, LJCA_MNG_GET_VERSION, NULL, 0, &version, &len, true,
> > > +			      LJCA_USB_WRITE_ACK_TIMEOUT_MS);
> > > +	if (ret)
> > > +		return ret;
> > > +
> > > +	if (len != sizeof(version)) {
> > > +		dev_err(&stub->intf->dev, "get version failed, len:%d\n", len);
> > > +		return -EINVAL;
> > > +	}
> > > +
> > > +	return sysfs_emit(buf, "%d.%d.%d.%d\n", version.major, version.minor,
> > > +			  le16_to_cpu(version.patch), le16_to_cpu(version.build));
> > > +}
> > 
> > You have sysfs files, yet no Documentation/ABI/ entries?  That's not
> > allowed, you know this :(
> The Documentation/ABI/ entries is added for the sysfs on patch 5 of this series.
> https://patchwork.kernel.org/project/linux-usb/patch/20230309071100.2856899-6-xiang.ye@intel.com/

Ah, missed that, sorry.

> > 
> > > +static ssize_t cmd_store(struct device *dev, struct device_attribute *attr, const char *buf,
> > > +			 size_t count)
> > > +{
> > > +	struct usb_interface *intf = to_usb_interface(dev);
> > > +	struct ljca_dev *ljca_dev = usb_get_intfdata(intf);
> > > +	struct ljca_stub *mng_stub = ljca_stub_find(ljca_dev, LJCA_MNG_STUB);
> > > +	struct ljca_stub *diag_stub = ljca_stub_find(ljca_dev, LJCA_DIAG_STUB);
> > > +
> > > +	if (sysfs_streq(buf, "dfu"))
> > > +		ljca_mng_set_dfu_mode(mng_stub);
> > > +	else if (sysfs_streq(buf, "debug"))
> > > +		ljca_diag_set_trace_level(diag_stub, 3);
> > 
> > Sorry, but no, you can't do this in a sysfs file.
> Do you mean that we can't use sysfs to send "debug" command to device?

That is correct, use the kernel-wide debugging facilities that we have
for this NEVER create your own custom interface just for one tiny
driver, that is not allowed.

> Could you provide some detail or hints?

dev_dbg().

thanks,

greg k-h