linux-kernel - Re: [PATCH v2 5/7] HID: ft260: improve i2c large reads performance

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Message-ID: <6ebd7f9424e43c70af4ada9fe5bf616d1a112bcc.camel@inka.de>
Date:   Wed, 05 Oct 2022 20:19:15 +0200
From:   Enrik Berkhan <Enrik.Berkhan@...a.de>
To:     Michael Zaidman <michael.zaidman@...il.com>
Cc:     jikos@...nel.org, linux-kernel@...r.kernel.org,
        linux-input@...r.kernel.org,
        Guillaume Champagne <champagne.guillaume.c@...il.com>
Subject: Re: [PATCH v2 5/7] HID: ft260: improve i2c large reads performance

Hi Michael,

On Wed, 2022-10-05 at 17:34 +0300, Michael Zaidman wrote:
> On Tue, Oct 04, 2022 at 08:15:56PM +0200, Enrik Berkhan wrote:
> > As the ft260 can pack up to 60 bytes into one report, would it make
> > sense to use a multiple-of-60 size (120 or 180)? Might reduce overhead
> > by another tiny bit ...
> > 
> > Cheers,
> > Enrik
> > 
> The size of the Read IO to perform is given to the driver by the upper
> layer. So it's up to him how to align the IO request size.
> 
> When we read from the EEPROM, we want to issue the read requests with
> EEPROM page size granularity. The I2C EEPROMs page sizes are usually a
> power of 2 aligned.

Understood! I only thought about the HID report sizes. With EEPROMs
etc. in mind, it makes perfect sense to prefer power of 2 sizes.

Thanks for also providing the test results.

Cheers,
Enrik