linux-kernel - Re: [PATCH v4 08/11] spi: aspeed: Calibrate read timings

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Date:   Thu, 31 Mar 2022 09:15:30 +0200
From:   Cédric Le Goater <clg@...d.org>
To:     Chin-Ting Kuo <chin-ting_kuo@...eedtech.com>,
        "linux-spi@...r.kernel.org" <linux-spi@...r.kernel.org>,
        "linux-mtd@...ts.infradead.org" <linux-mtd@...ts.infradead.org>
CC:     "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        Vignesh Raghavendra <vigneshr@...com>,
        "linux-aspeed@...ts.ozlabs.org" <linux-aspeed@...ts.ozlabs.org>,
        Tudor Ambarus <tudor.ambarus@...rochip.com>,
        Richard Weinberger <richard@....at>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Brown <broonie@...nel.org>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Pratyush Yadav <p.yadav@...com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v4 08/11] spi: aspeed: Calibrate read timings

Hello Chin-Ting,

>>> - Maybe, if the calibration process is not executed, the frequency setting
>> calculated from max_frequency in the device tree can be filled in FMC10
>> instead of using dumb slow one, 12.5MHz, always.
>>
>> Indeed.
>>
>>>    For example, except for uniform content case, the calibration process will
>> be ignored when SPI clock frequency in the device tree is smaller than 40MHz.
>>> - The function, aspeed_2600_spi_clk_basic_setting, in [2] can be added to
>> support lower SPI clock frequency, e.g., 4MHz.
>>>    For AST2600, SPI clock frequency can be calculated by
>> HCLK/(FMC10[27:24] + FMC10[11:8]).
>>
>> Could you please send patches on top of this series ? Here are the branches :
>>
> 
> Of course. How do I provide you the patch? By private mail or send a PR?

We should discuss first by email on the openbmc@ and linux-aspeed@ lists.
Please send as follow ups on top of v4.

Using the openbmc tree should be easier :

      https://github.com/legoater/linux/commits/openbmc-5.15

> Besides, I may add a new callback function for this part due to difference 
> between AST2500 and AST2600.

ok.

Given all the reviews and tests that were done on AST2400, AST2500, AST2600
platforms, I will be careful not to break the existing proposal.

Thanks,

C.