linux-kernel - Re: [PATCH] mtd: nand: raw: qcom_nandc: Don't clear_bam

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Message-ID: <796a60da-2fe5-1712-ed78-d5bb8050779c@somainline.org>
Date:   Thu, 13 Jan 2022 19:45:40 +0100
From:   Konrad Dybcio <konrad.dybcio@...ainline.org>
To:     ~postmarketos/upstreaming@...ts.sr.ht
Cc:     martin.botka@...ainline.org,
        angelogioacchino.delregno@...ainline.org,
        marijn.suijten@...ainline.org, jamipkettunen@...ainline.org,
        Manivannan Sadhasivam <mani@...nel.org>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>,
        linux-mtd@...ts.infradead.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mtd: nand: raw: qcom_nandc: Don't clear_bam_transaction
 on READID



On 13.01.2022 19:44, Konrad Dybcio wrote:
> While I have absolutely 0 idea why and how, running clear_bam_transaction
> when READID is issued makes the DMA totally clog up and refuse to function
> at all on mdm9607. In fact, it is so bad that all the data gets garbled
> and after a short while in the nand probe flow, the CPU decides that
> sepuku is the only option.
> 
> Removing _READID from the if condition makes it work like a charm, I can
> read data and mount partitions without a problem.
> 
> Signed-off-by: Konrad Dybcio <konrad.dybcio@...ainline.org>
> ---
> This is totally just an observation which took me an inhumane amount of
> debug prints to find.. perhaps there's a better reason behind this, but
> I can't seem to find any answers.. Therefore, this is a BIG RFC!
> 
Somehow I didn't put RFC in the title though, sorry!

Konrad