Re: [PATCH V15 3/6] i2c: tegra: fix maximum transfer size

Dmitry Osipenko
2019-02-08T12:46:50Z

08.02.2019 1:25, Dmitry Osipenko пишет:
>> 08.02.2019 1:16, Sowjanya Komatineni пишет:>
>>>> This is wrong, 65535 = 64 * 1024 - 1.
>>>>
>>>> Let's just use size-constants provided by kernel:
>>>>
>>>> static const struct i2c_adapter_quirks tegra_i2c_quirks = {
>>>> .flags = I2C_AQ_NO_ZERO_LEN,
>>>> .max_read_len = SZ_4K,
>>>> .max_write_len = SZ_4K - I2C_PACKET_HEADER_SIZE, };
>>>>
>>>> static const struct i2c_adapter_quirks tegra194_i2c_quirks = {
>>>> .flags = I2C_AQ_NO_ZERO_LEN,
>>>> .max_read_len = SZ_64K,
>>>> .max_write_len = SZ_64K - I2C_PACKET_HEADER_SIZE, };
>>>>
>>>>
>>>> I'll take a look at other patches later today, no need to send out new version right now.
>>>>
>>>>
>>>
>>> SIZE_64K is 0x00010000 (65536)
>>>
>>> msg len is u16 and max that can be set to msg.len is 65535
>
> Ah, okay. Then it looks about right, maybe it's time to change u16 to u32 in the I2C core.
>

Here is my suggestion:

1) Use SZ_4K / SZ_64K that I suggested above.

2) Squash this patch into the DMA-patch.

3) Add another patch (before the DMA-patch) that changes max_read_len/max_write_len types to u32 in the include/linux/i2c.h