Re: [PATCH V2 05/13] pm80xx : Support for char device.

John Garry
2020-01-22T12:39:02Z

On 22/01/2020 08:50, Deepak.Ukey@microchip.com wrote:
> -r--r--r-- 1 root root 4096 Jan 21 12:05 running_disparity_error_count ***
> -r--r--r-- 1 root root 4096 Jan 21 12:05 sas_address
> lrwxrwxrwx 1 root root 0 Jan 21 11:45 subsystem ->
> ../../../../../../../class/sas_phy
> -r--r--r-- 1 root root 4096 Jan 21 12:05 target_port_protocols
> -rw-r--r-- 1 root root 4096 Jan 21 11:45 uevent
>
> Maybe the other stuff provided in the patches are useful, I don't know.
> But debugfs seems better for that.
>
> - 0006-pm80xx-sysfs-attribute-for-number-of-phys
> - 0007-pm80xx-IOCTL-functionality-to-get-phy-status gets things like Programmed Link Rate, Negotiated Link Rate, PHY Identifier
> - 0008-pm80xx-IOCTL-functionality-to-get-phy-error provides other things like Invalid Dword Error Count, Disparity Error Count
> - Thanks for addressing it. We can get this info from /sys/class/sas_phy and /sys/class/sas_port so we will drop these above mentioned three patches from the next - patch series.
>
> > 0009-pm80xx-IOCTL-functionality-for-GPIO
> > 0010-pm80xx-IOCTL-functionality-for-SGPIO
>
> I don't know why an ioctl is required here.
>
> > 0013-pm80xx-IOCTL-functionality-for-TWI-device
>
> - 0009-pm80xx-IOCTL-functionality-for-GPIO
> - 0010-pm80xx-IOCTL-functionality-for-SGPIO
> - 0013-pm80xx-IOCTL-functionality-for-TWI-device
> - For the above patches management utility passes command specific information to driver through IOCTL structure, which used by driver to frame the command and - send to FW. We are using the IOCTL interface for the same. Please let us know your thought.

So I specifically questioned the SGPIO patch and why it would have an
IOCTL, as this function is supported in kernel libsas/SAS transport code
as an SMP function.

For the GPIO IOCTL, could you use register a gpio driver to provide a
gpiolib sysfs?

As for TWI, it seems to be for serial EEPROM, so you could ask these
experts about how to handle it properly in the kernel for standard sysfs
interfaces:

:~/linux$ ./scripts/get_maintainer.pl -f drivers/misc/eeprom/eeprom.c
Jean Delvare <jdelvare@suse.com> (maintainer:LEGACY EEPROM DRIVER)
Arnd Bergmann <arnd@arndb.de> (supporter:CHAR and MISC DRIVERS)
Greg Kroah-Hartman <gregkh@linuxfoundation.org> (supporter:CHAR and MISC
DRIVERS)

Thanks,
John