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

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Date:   Wed, 26 Jan 2022 16:03:16 +0530
From:   Manivannan Sadhasivam <mani@...nel.org>
To:     Miquel Raynal <miquel.raynal@...tlin.com>
Cc:     Konrad Dybcio <konrad.dybcio@...ainline.org>,
        ~postmarketos/upstreaming@...ts.sr.ht, martin.botka@...ainline.org,
        angelogioacchino.delregno@...ainline.org,
        marijn.suijten@...ainline.org, jamipkettunen@...ainline.org,
        Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>,
        linux-mtd@...ts.infradead.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org, mdalam@...eaurora.org,
        sricharan@...eaurora.org
Subject: Re: [PATCH] mtd: nand: raw: qcom_nandc: Don't clear_bam_transaction
 on READID

On Wed, Jan 26, 2022 at 11:16:13AM +0100, Miquel Raynal wrote:
> Hello,
> 
> miquel.raynal@...tlin.com wrote on Fri, 14 Jan 2022 08:27:18 +0100:
> 
> > Hi Konrad,
> > 
> > konrad.dybcio@...ainline.org wrote on Thu, 13 Jan 2022 19:44:26 +0100:
> > 
> > > 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!  
> > 
> > I'm adding two people from codeaurora who worked a lot on this driver.
> > Hopefully they will have an idea :)
> 
> Sadre, I've spent a significant amount of time reviewing your patches,
> now it's your turn to not take a month to answer to your peers
> proposals.
> 
> Please help reviewing this patch.
> 

Sorry. I was hoping that Qcom folks would chime in as I don't have any idea
about the mdm9607 platform. It could be that the mail server migration from
codeaurora to quicinc put a barrier here.

Let me ping them internally.

> BTW why is this driver still using cmdfund? It should have been
> migrated to ->exec_op() a long time ago.

I'll look into it.

Thanks,
Mani
> 
> Thanks,
> Miquèl