Re: [PATCH] wifi: rtlwifi: Drastically reduce the attempts to read efuse bytes in case of failures

["Guilherme G. Piccoli" <gpiccoli@igalia.com>]

On 27/10/2024 22:44, Ping-Ke Shih wrote:
> Guilherme G. Piccoli <gpiccoli@igalia.com> wrote:
>>
>> This procedure for reading efuse bytes relies in a loop that performs an
>> I/O read up to *10k* times in case of failures. We measured the time of
>> the loop inside read_efuse_byte() alone, and in this reproducer (which
>> involves the dummy_hcd emulation layer), it takes 15 seconds each.
> 
> The I/O read of 10k times is to polling if efuse is ready, and then following
> statement is to actually read efuse content back. For USB devices, I/O is
> slow, so it might be fine to reduce retry times. But For PCIE devices,
> I think this will be risky without testing with real hardware.
> 
> Possible way is to use "rtlhal->interface == INTF_PCI" to keep original times
> for PCIE devices, and only reduce retry times for USB devices. But USB can
> operate on USB-2/-3 modes, so maybe still need experiments with real hardware 
> to get reasonable retry times. 
> 

Thanks a bunch for the review and extra details Ping-Ke Shih!

The idea of guarding with "rtlhal->interface == INTF_PCI" is very good
and I can implement in a V2.

But can you help me on finding a USB adapter that runs this path? If you
know a commodity model that uses this specific driver, could you point
me so I can buy one for testing?

Meanwhile I'll try to find a model based on some kernel reports online,
hope I can!

Cheers,


Guilherme