From: Christoph Hellwig <hch@lst.de>
To: Lauri Kasanen <cand@gmx.com>
Cc: Christoph Hellwig <hch@lst.de>,
axboe@kernel.dk, linux-block@vger.kernel.org
Subject: Re: [PATCH] n64cart: fix the dma address in n64cart_do_bvec
Date: Wed, 4 Aug 2021 12:02:03 +0200 [thread overview]
Message-ID: <20210804100203.GA20072@lst.de> (raw)
In-Reply-To: <20210804130136.55f633eeb4522f844463159a@gmx.com>
On Wed, Aug 04, 2021 at 01:01:36PM +0300, Lauri Kasanen wrote:
> > diff --git a/drivers/block/n64cart.c b/drivers/block/n64cart.c
> > index 7b4dd10af9ec..c84be0028f63 100644
> > --- a/drivers/block/n64cart.c
> > +++ b/drivers/block/n64cart.c
> > @@ -74,7 +74,7 @@ static bool n64cart_do_bvec(struct device *dev, struct bio_vec *bv, u32 pos)
> >
> > n64cart_wait_dma();
> >
> > - n64cart_write_reg(PI_DRAM_REG, dma_addr + bv->bv_offset);
> > + n64cart_write_reg(PI_DRAM_REG, dma_addr);
> > n64cart_write_reg(PI_CART_REG, (bstart | CART_DOMAIN) & CART_MAX);
> > n64cart_write_reg(PI_WRITE_REG, bv->bv_len - 1);
>
> Hm, then how did it work? Does it always happen to be zero?
It isn't always zero, but for your use cases it might. That is if
you have a page aligned buffer (e.g. the page cache) it tends to be
zero.
> Have you tested this? I don't have the equipment currently.
No, I don't. I'm just auditing uses of bv_offset and this one is
clearly bogus.
next prev parent reply other threads:[~2021-08-04 10:02 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-04 9:49 [PATCH] n64cart: fix the dma address in n64cart_do_bvec Christoph Hellwig
2021-08-04 10:01 ` Lauri Kasanen
2021-08-04 10:02 ` Christoph Hellwig [this message]
2021-08-04 10:16 ` Lauri Kasanen
2021-08-04 17:15 ` Jens Axboe
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