linux-kernel - Re: [PATCH v7 char-misc-next] misc: microchip: pci1xxxx: Add OTP/EEPROM driver for the pci1xxxx switch

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Message-ID: <ZA9Me2d9IsoYGifp@kroah.com>
Date:   Mon, 13 Mar 2023 17:16:59 +0100
From:   Greg KH <gregkh@...uxfoundation.org>
To:     VaibhaavRam.TL@...rochip.com
Cc:     arnd@...db.de, Kumaravel.Thiagarajan@...rochip.com,
        linux-kernel@...r.kernel.org, UNGLinuxDriver@...rochip.com,
        Tharunkumar.Pasumarthi@...rochip.com
Subject: Re: [PATCH v7 char-misc-next] misc: microchip: pci1xxxx: Add
 OTP/EEPROM driver for the pci1xxxx switch

On Mon, Mar 13, 2023 at 04:01:15PM +0000, VaibhaavRam.TL@...rochip.com wrote:
> > Again, default group will handle this automatically, you should never 
> > need to call a sysfs_*() call from a driver.  Otherwise something is usually very wrong.
> 
> Are you recommending similar to this snippet?
> 
> static struct bin_attribute *pci1xxxx_bin_attributes[] = {
> 	&pci1xxxx_otp_attr,
> 	&pci1xxxx_eeprom_attr
> 	NULL,
> };
> 
> static const struct attribute_group pci1xxxx_bin_attributes_group = {
> 	.bin_attrs = pci1xxxx_bin_attributes,
> };
> ..
> ..
> auxiliary_device.device.attribute_group = pci1xxxx_bin_attributes_group

Yes.

> This creates sysfs for both EEPROM and OTP at once and handles for its removal, right?
> But, In this case, I have to check whether EEPROM is responsive and only then create sysfs for it.
> 
> Can you please provide some guidance, on how to handle this situation without using sysfs_*().

Use the "is_visible" callback in your group to tell the driver core if
the specific attribute needs to be created or not.

thanks,

greg k-h