Re: [PATCH v2 4/6] dmaengine: dw: Print warning if multi-block is unsupported

From: Mark Brown
Date: Mon May 11 2020 - 17:32:28 EST


On Mon, May 11, 2020 at 09:32:47PM +0300, Serge Semin wrote:

> Thanks for the explanation. Max segment size being set to the DMA controller generic
> device should work well. There is no need in setting the transfer and messages
> size limitations. Besides I don't really see the
> max_transfer_size/max_message_size callbacks utilized in the SPI core. These
> functions are called in the spi-mem.c driver only. Do I miss something?

We really should validate them in the core but really they're intended
for client drivers (like spi-mem kind of is) to allow them to adapt the
sizes of requests they're generating so the core never sees anything
that's too big. For the transfers we have a spi_split_transfers_maxsize()
helper if anything wants to use it. Fortunately there's not that many
controllers with low enough limits to worry about so actual usage hasn't
been that high.

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