linux-kernel - Re: [PATCH v3 2/5] mtd: nand: Qualcomm NAND controller driver

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Date:	Tue, 04 Aug 2015 10:53:34 -0700
From:	Stephen Boyd <sboyd@...eaurora.org>
To:	Archit Taneja <architt@...eaurora.org>
CC:	dehrenberg@...gle.com, linux-arm-msm@...r.kernel.org,
	cernekee@...il.com, linux-kernel@...r.kernel.org,
	linux-mtd@...ts.infradead.org, agross@...eaurora.org,
	computersforpeace@...il.com
Subject: Re: [PATCH v3 2/5] mtd: nand: Qualcomm NAND controller driver

On 08/04/2015 08:04 AM, Archit Taneja wrote:
>
> On 8/4/2015 5:08 AM, Stephen Boyd wrote:
>> I also wonder if this is little endian? It looks like some sort
>> of in memory register map that we point DMA to so that it can
>> write the values to the actual hardware registers?
>
> Yes, that's what it's supposed to do. I kept it in the form above
> so that updating the register map is as easy as assigning a new
> value to the member.
>
> I've tried to fix it for endianness in the diff below. I created
> some funcs to not flood the driver with cpu_to_le32() calls. Does
> it look okay?
>

Looks good.

>>
>>> +
>>> +    return 0;
>>> +}
>>> +
>> [...]
>>> +
>>> +/*
>>> + * this is called after NAND_CMD_PAGEPROG and NAND_CMD_ERASE1 to 
>>> set our
>>> + * privately maintained status byte, this status byte can be read 
>>> after
>>> + * NAND_CMD_STATUS is called
>>> + */
>>> +static void parse_erase_write_errors(struct qcom_nandc_data *this, 
>>> int command)
>>> +{
>>> +    struct nand_chip *chip = &this->chip;
>>> +    struct nand_ecc_ctrl *ecc = &chip->ecc;
>>> +    int num_cw;
>>> +    int i;
>>> +
>>> +    num_cw = command == NAND_CMD_PAGEPROG ? ecc->steps : 1;
>>> +
>>> +    for (i = 0; i < num_cw; i++) {
>>> +        __le32 flash_status = le32_to_cpu(this->reg_read_buf[i]);
>>
>> So this doesn't need the i * 3 thing? If it does, perhaps
>> reg_read_buf needs to be of type struct read_stats instead.
>
> We just read back one register per codeword here, so we can't do
> the read_stats thing as before. I could read back the extra registers
> and discrading them, but I'd I'll leave that for later.

Ah right. Sounds like nothing to change then.

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

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