From mboxrd@z Thu Jan  1 00:00:00 1970
From: Boris Brezillon <boris.brezillon@collabora.com>
Subject: Re: [PATCH v2 2/2] spi: npcm-fiu: add NPCM FIU controller driver
Date: Fri, 9 Aug 2019 17:25:57 +0200
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To: Tomer Maimon <tmaimon77@gmail.com>
Cc: Mark Brown <broonie@kernel.org>, Rob Herring <robh+dt@kernel.org>, Mark Rutland <mark.rutland@arm.com>, Vignesh Raghavendra <vigneshr@ti.com>, Boris Brezillon <bbrezillon@kernel.org>, Avi Fishman <avifishman70@gmail.com>, Tali Perry <tali.perry1@gmail.com>, Patrick Venture <venture@google.com>, Nancy Yuen <yuenn@google.com>, Benjamin Fair <benjaminfair@google.com>, linux-spi@vger.kernel.org, devicetree <devicetree@vger.kernel.org>, OpenBMC Maillist <openbmc@lists.ozlabs.org>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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On Fri, 9 Aug 2019 18:26:23 +0300
Tomer Maimon <tmaimon77@gmail.com> wrote:

> Hi Boris,
> 
> Thanks a lot for your comment.
> 
> On Thu, 8 Aug 2019 at 18:32, Boris Brezillon <boris.brezillon@collabora.com>
> wrote:
> 
> > On Thu,  8 Aug 2019 16:14:48 +0300
> > Tomer Maimon <tmaimon77@gmail.com> wrote:
> >
> >  
> > > +
> > > +static const struct spi_controller_mem_ops npcm_fiu_mem_ops = {
> > > +     .exec_op = npcm_fiu_exec_op,  
> >
> > No npcm_supports_op()? That's suspicious, especially after looking at
> > the npcm_fiu_exec_op() (and the functions called from there) where the
> > requested ->buswidth seems to be completely ignored...
> >
> > Sorry but I do not fully understand it, do you mean a support for the  
> buswidth?
> If yes it been done in the UMA functions as follow:
> 
>                 uma_cfg |= ilog2(op->cmd.buswidth);
>                 uma_cfg |= ilog2(op->addr.buswidth) <<
>                         NPCM_FIU_UMA_CFG_ADBPCK_SHIFT;
>                 uma_cfg |= ilog2(op->data.buswidth) <<
>                         NPCM_FIU_UMA_CFG_WDBPCK_SHIFT;
>                 uma_cfg |= op->addr.nbytes << NPCM_FIU_UMA_CFG_ADDSIZ_SHIFT;
>                 regmap_write(fiu->regmap, NPCM_FIU_UMA_ADDR, op->addr.val);
>

Hm, the default supports_op() implementation might be just fine for
your use case. But there's one thing you still need to check: the
number of addr cycles (or address size as you call it in this driver).
Looks like your IP is limited to 4 address cycles, if I'm right, you
should reject any operation that have op->addr.nbytes > 4. I also
wonder if there's a limitation on the data size you can have on a
single transfer. If there's one you should implement ->adjust_op() too.