linux-kernel - Re: [PATCH] spi: spi-sun6i: implement DMA-based transfer mode

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Message-ID: <CAGb2v64ruUf7Lv-cHZTRPs-U-gOboGtTwOB3+qtxZTFyLVFLjg@mail.gmail.com>
Date:   Tue, 20 Oct 2020 11:52:34 +0800
From:   Chen-Yu Tsai <wens@...e.org>
To:     Alexander Kochetkov <al.kochet@...il.com>
Cc:     Maxime Ripard <maxime@...no.tech>, Mark Brown <broonie@...nel.org>,
        linux-spi@...r.kernel.org,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] spi: spi-sun6i: implement DMA-based transfer mode

On Tue, Oct 20, 2020 at 1:43 AM Alexander Kochetkov <al.kochet@...il.com> wrote:
>
>
>
> > 19 окт. 2020 г., в 11:21, Maxime Ripard <maxime@...no.tech> написал(а):
> >
> > Hi!
> >
> > On Thu, Oct 15, 2020 at 06:47:40PM +0300, Alexander Kochetkov wrote:
> >> DMA-based transfer will be enabled if data length is larger than FIFO size
> >> (64 bytes for A64). This greatly reduce number of interrupts for
> >> transferring data.
> >>
> >> For smaller data size PIO mode will be used. In PIO mode whole buffer will
> >> be loaded into FIFO.
> >>
> >> If driver failed to request DMA channels then it fallback for PIO mode.
> >>
> >> Tested on SOPINE (https://www.pine64.org/sopine/)
> >>
> >> Signed-off-by: Alexander Kochetkov <al.kochet@...il.com>
> >
> > Thanks for working on this, it's been a bit overdue
>
> Hi, Maxime!
>
> We did custom A64 based computation module for our product.
> Do you mean that A64 is obsolete or EOL product?
> If so, can you recommend active replacement for A64 from Allwinner same price?

I believe what Maxime meant was that DMA transfer for SPI is a long
sought-after feature, but no one had finished it.

ChenYu