linux-kernel - Re: [PATCH v3 11/11] serial: sc16is7xx: add dump registers function

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Date:   Thu, 25 May 2023 14:26:43 +0300
From:   andy.shevchenko@...il.com
To:     Hugo Villeneuve <hugo@...ovil.com>
Cc:     gregkh@...uxfoundation.org, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
        jirislaby@...nel.org, jringle@...dpoint.com,
        tomasz.mon@...lingroup.com, l.perczak@...lintechnologies.com,
        linux-serial@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-gpio@...r.kernel.org,
        Hugo Villeneuve <hvilleneuve@...onoff.com>
Subject: Re: [PATCH v3 11/11] serial: sc16is7xx: add dump registers function

Thu, May 25, 2023 at 12:03:25AM -0400, Hugo Villeneuve kirjoitti:
> From: Hugo Villeneuve <hvilleneuve@...onoff.com>
> 
> With this driver, it is very hard to debug the registers using
> the /sys/kernel/debug/regmap interface.
> 
> The main reason is that bits 0 and 1 of the register address
> correspond to the channels bits, so the register address itself starts
> at bit 2, so we must 'mentally' shift each register address by 2 bits
> to get its offset.
> 
> Also, only channels 0 and 1 are supported, so combinations of bits
> 0 and 1 being 10b and 11b are invalid, and the display of these
> registers is useless.
> 
> For example:
> 
> cat /sys/kernel/debug/regmap/spi0.0/registers
> 04: 10 -> Port 0, register offset 1
> 05: 10 -> Port 1, register offset 1
> 06: 00 -> Port 2, register offset 1 -> invalid
> 07: 00 -> port 3, register offset 1 -> invalid
> ...
> 
> Add a debug module parameter to call a custom dump function for each
> port registers after the probe phase to help debug.

Not sure about this. Can we rather create an abstract mapping on regmap?
(Something like gpio-pca953x.c has)

-- 
With Best Regards,
Andy Shevchenko