linux-kernel - Re: [PATCH v2 1/2] mtd: rawnand: qcom: Fix broken erase in misc_cmd_type in exec

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Message-ID: <6604302e.5d0a0220.bdb64.4077@mx.google.com>
Date: Wed, 27 Mar 2024 15:41:47 +0100
From: Christian Marangi <ansuelsmth@...il.com>
To: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Cc: Miquel Raynal <miquel.raynal@...tlin.com>,
	Richard Weinberger <richard@....at>,
	Vignesh Raghavendra <vigneshr@...com>,
	Md Sadre Alam <quic_mdalam@...cinc.com>,
	Sricharan Ramabadhran <quic_srichara@...cinc.com>,
	linux-mtd@...ts.infradead.org, linux-arm-msm@...r.kernel.org,
	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH v2 1/2] mtd: rawnand: qcom: Fix broken erase in
 misc_cmd_type in exec_op

On Tue, Mar 26, 2024 at 01:09:47PM +0530, Manivannan Sadhasivam wrote:
> On Tue, Mar 26, 2024 at 12:55:19PM +0530, Manivannan Sadhasivam wrote:
> > On Mon, Mar 25, 2024 at 11:30:47AM +0100, Christian Marangi wrote:
> > > misc_cmd_type in exec_op have multiple problems. With commit a82990c8a409
> > > ("mtd: rawnand: qcom: Add read/read_start ops in exec_op path") it was
> > > reworked and generalized but actually broke the handling of the
> > > ERASE_BLOCK command.
> > > 
> > > Additional logic was added to the erase command cycle without clear
> > > explaination causing the erase command to be broken on testing it on
> > > a ipq806x nandc.
> > > 
> > > Fix the erase command by reverting the additional logic and only adding
> > > the NAND_DEV0_CFG0 additional call (required for erase command).
> > > 
> > > Fixes: a82990c8a409 ("mtd: rawnand: qcom: Add read/read_start ops in exec_op path")
> > > Cc: stable@...r.kernel.org
> > > Signed-off-by: Christian Marangi <ansuelsmth@...il.com>
> > > ---
> > > Changes v2:
> > > - Split this and rework commit description and title
> > > 
> > >  drivers/mtd/nand/raw/qcom_nandc.c | 5 ++---
> > >  1 file changed, 2 insertions(+), 3 deletions(-)
> > > 
> > > diff --git a/drivers/mtd/nand/raw/qcom_nandc.c b/drivers/mtd/nand/raw/qcom_nandc.c
> > > index b079605c84d3..19d76e345a49 100644
> > > --- a/drivers/mtd/nand/raw/qcom_nandc.c
> > > +++ b/drivers/mtd/nand/raw/qcom_nandc.c
> > > @@ -2830,9 +2830,8 @@ static int qcom_misc_cmd_type_exec(struct nand_chip *chip, const struct nand_sub
> > >  	nandc_set_reg(chip, NAND_EXEC_CMD, 1);
> > >  
> > >  	write_reg_dma(nandc, NAND_FLASH_CMD, instrs, NAND_BAM_NEXT_SGL);
> > > -	(q_op.cmd_reg == OP_BLOCK_ERASE) ? write_reg_dma(nandc, NAND_DEV0_CFG0,
> > > -	2, NAND_BAM_NEXT_SGL) : read_reg_dma(nandc,
> > > -	NAND_FLASH_STATUS, 1, NAND_BAM_NEXT_SGL);
> > > +	if (q_op.cmd_reg == OP_BLOCK_ERASE)
> > > +		write_reg_dma(nandc, NAND_DEV0_CFG0, 2, NAND_BAM_NEXT_SGL);
> > 
> > So this only avoids the call to, 'read_reg_dma(nandc, NAND_FLASH_STATUS, 1,
> > NAND_BAM_NEXT_SGL)' if q_op.cmd_reg != OP_BLOCK_ERASE. But for q_op.cmd_reg ==
> > OP_BLOCK_ERASE, the result is the same.
> > 
> > I'm wondering how it results in fixing the OP_BLOCK_ERASE command.
> > 
> 
> Perhaps you are trying to fix the OP_RESET_DEVICE command altogether?
>

Well with this only patch correct working of nandc on ipq806x is
restored. I'm still very confused how since the misc command currently
works only with the PROGRAM_PAGE and the BLOCK_ERASE (from ERASE1 and
ERASE2)

Still the extra read was added with no explaination and I couldn't find
this command cycle in any of the previous legacy function and the one
introduced after the parser rework.

-- 
	Ansuel