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SubjectRe: [PATCH 4/5] mtd: spi-nor: Add driver for Adaptrum Anarion QSPI controller
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On 07/31/2017 02:33 PM, Marek Vasut wrote:
> On 07/31/2017 07:17 PM, Alexandru Gagniuc wrote:

Hi Marek,

Thank you again for your feedback. I've applied a majority of your
suggestions, and I am very happy with the result. I should have v2
posted within a day or so.

[snip]
>>>> +/*
>>>> + * This mask does not match reality. Get over it:
>>>
>>> What is this about ?
>>
>> Each stage of the QSPI chain has two registers. The second register has
>> a bitfield which takes in the length of the stage. For example, for
>> DATA2, we can set the length up to 0x4000, but for ADDR2, we can only
>> set a max of 4 bytes. I wrote this comment as a reminder to myself to be
>> careful about using this mask. I'll rephrase the comment for [v2]
>
> Please do.
>
Staged for [PATCH v2]

>>>> + * DATA2: 0x3fff
>>>> + * CMD2: 0x0003
>>>> + * ADDR2: 0x0007
>>>> + * PERF2: 0x0000
>>>> + * HI_Z: 0x003f
>>>> + * BCNT: 0x0007
>>>> + */
>>>> +#define CHAIN_LEN(x) ((x - 1) & ASPI_DATA_LEN_MASK)
>>>> +
>>>> +struct anarion_qspi {
>>>> + struct spi_nor nor;
>>>> + struct device *dev;
>>>> + uintptr_t regbase;
>>>
>>> Should be void __iomem * I guess ?
>>
>> I chose uintptr_t as opposed to void *, because arithmetic on void * is
>> not valid in C. What is the right answer hen, without risking undefined
>> behavior?
>
> What sort of arithmetic ? It's perfectly valid in general ...

ISO/IEC 9899:201x, Section 6.5.6, constraint(2) is not met when the one
of the operands to addition is a void pointer.
Section 6.2.5 (19) defines void to be an incomplete type.

[snip]

>>> Is this stuff below something like ioread32_rep() ?
>>>
>>>> + aspi_write_reg(aspi, ASPI_REG_BYTE_COUNT, sizeof(uint32_t));
>>>> + while (len >= 4) {
>>>> + data = aspi_read_reg(aspi, ASPI_REG_DATA1);
>>>> + memcpy(buf, &data, sizeof(data));
>>>> + buf += 4;
>>>> + len -= 4;
>>>> + }
>>
>> That is very similar to ioread32_rep, yes. I kept this as for the
>> reasons outlined above, but changing this to _rep() seems innocent enough.
>
> What reason ?

Being able to share the code between the different codebases where it is
used.

Alex

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