Re: [PATCH 14/15] can: tcan4x5x: Fix register range of first block - Markus Schneider-Pargmann

From: Markus Schneider-Pargmann <msp@baylibre.com>
To: Marc Kleine-Budde <mkl@pengutronix.de>
Cc: Chandrasekar Ramakrishnan <rcsekar@samsung.com>,
	Wolfgang Grandegger <wg@grandegger.com>,
	linux-can@vger.kernel.org, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 14/15] can: tcan4x5x: Fix register range of first block
Date: Mon, 5 Dec 2022 10:55:23 +0100	[thread overview]
Message-ID: <20221205095523.sy3piugsrvik2zz3@blmsp> (raw)
In-Reply-To: <20221205094458.xkvlvp7fnygf23fq@pengutronix.de>

On Mon, Dec 05, 2022 at 10:44:58AM +0100, Marc Kleine-Budde wrote:
> On 05.12.2022 10:30:13, Markus Schneider-Pargmann wrote:
> > Hi Marc,
> > 
> > On Fri, Dec 02, 2022 at 03:28:10PM +0100, Marc Kleine-Budde wrote:
> > > On 16.11.2022 21:53:07, Markus Schneider-Pargmann wrote:
> > > > According to the datasheet 0x1c is the last register in the first block,
> > > > not register 0x2c.
> > > 
> > > The datasheet "SLLSF91A – DECEMBER 2018 – REVISED JANUARY 2020" says:
> > > 
> > > | 8.6.1 Device ID and Interrupt/Diagnostic Flag Registers: 16'h0000 to
> > > | 16'h002F
> > > 
> > > While the last described register is at 0xc.
> > 
> > Sorry, not sure what I looked up here. The last described register is
> > 0x10 SPI Error status mask in my datasheet:
> > 'SLLSEZ5D – JANUARY 2018 – REVISED JUNE 2022'
> 
> The TCAN4550-Q1 variant has the 0x10 register documented, while the
> TCAN4550 (w/o -Q1) doesn't have.

Ah haven't noticed, thank you.

> 
> > I would prefer using the actual registers if that is ok with you, so
> > 0x10 here because I assume the remaining registers have internal use or
> > maybe don't exist at all?! If there is an undocumented register that
> > needs to be used at some point we can still modify the ranges.
> 
> I'm fine with using 0x10 as the last register.
> 
> > Also it seems the existing ranges are following the same logic and don't
> > list the whole range, just the documented registers.
> > 
> > The second range is wrong as well. The last register is 0x830, will
> > fix.
> 
> IIRC I used the register ranges from the section titles ("8.6.1 Device
> ID and Interrupt/Diagnostic Flag Registers: 16'h0000 to 16'h002F") when
> I added the {wr,rd}_table.

The second range in the driver was specified as 0x800-0x83c in the
driver. The last documented register is 0x830 in both normal and Q1
versions while the range in the title is 0x800-0x8ff. That's why I
thought it was using the last register, just because it is closer.

Anyways not really important.

I can put in whatever you feel comfortable with or keep as it is.

Thanks,
Markus