From: Feng Tang <feng.tang@intel.com>
To: Dirk Brandewie <dirk.brandewie@gmail.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"spi-devel-general@lists.sourceforge.net"
<spi-devel-general@lists.sourceforge.net>
Subject: Re: [PATCH 09/11] spi-dw: Fix condition in spi_dw_{writer/reader}
Date: Thu, 23 Jun 2011 11:25:52 +0800 [thread overview]
Message-ID: <20110623112552.6f22c3de@feng-i7> (raw)
In-Reply-To: <4E02AE6E.5010307@gmail.com>
On Thu, 23 Jun 2011 11:09:34 +0800
Dirk Brandewie <dirk.brandewie@gmail.com> wrote:
> On 06/22/2011 07:45 PM, Feng Tang wrote:
> > On Thu, 23 Jun 2011 10:00:11 +0800
> > "dirk.brandewie@gmail.com"<dirk.brandewie@gmail.com> wrote:
> >
> >> From: Dirk Brandewie<dirk.brandewie@gmail.com>
> >>
> >> Fix the condition based on whether the current transfer has a tx/rx
> >> buffer.
> >>
> >> Signed-off-by: Dirk Brandewie<dirk.brandewie@gmail.com>
> >> ---
> >> drivers/spi/spi-dw.c | 6 +++---
> >> 1 files changed, 3 insertions(+), 3 deletions(-)
> >>
> >> diff --git a/drivers/spi/spi-dw.c b/drivers/spi/spi-dw.c
> >> index cc38aa0..35b952b 100644
> >> --- a/drivers/spi/spi-dw.c
> >> +++ b/drivers/spi/spi-dw.c
> >> @@ -193,8 +193,8 @@ static void spi_dw_writer(struct spi_dw *dws)
> >> u16 txw = 0;
> >>
> >> while (max--) {
> >> - /* Set the tx word if the transfer's original "tx"
> >> is not null */
> >> - if (dws->tx_end - dws->len) {
> >> + /* Set the tx word if the transfer's "tx" is not
> >> null */
> >> + if (dws->tx) {
> >
> > No, in current mainstream code, the dws->tx is changing, see code:
> > dws->tx += dws->n_bytes;
> > so we have to use if (dws->tx_end - dws->len) for now, maybe
> > we can use some bit to indicate whether the original tx is null
>
> If dws->tx is non-null then it points to a valid buffer, it is
> unconditionally set with dws->tx = (void *)transfer->tx_buf when the
> transfer is setup. if the original transfer->tx_buf is non-null then
> this change works.
dws->tx is changing as I said, non-null doesn't mean the value is valid,
when the original tx is null, we don't access it at all, it's just a
indicator of whether the dws->len of zeor has been filled to FIFO.
This logic may looks confusing, but it's correct after years of test.
>
> >
> >> if (dws->n_bytes == 1)
> >> txw = *(u8 *)(dws->tx);
> >> else
> >> @@ -213,7 +213,7 @@ static void spi_dw_reader(struct spi_dw *dws)
> >> while (max--) {
> >> rxw = dw_readw(dws, dr);
> >> /* Care rx only if the transfer's original "rx"
> >> is not null */
> >> - if (dws->rx_end - dws->len) {
> >> + if (dws->rx) {
> >> if (dws->n_bytes == 1)
> >> *(u8 *)(dws->rx) = rxw;
> >> else
>
next prev parent reply other threads:[~2011-06-23 3:25 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-06-23 2:00 [PATCH 00/11] RFC spi-dw updates dirk.brandewie
2011-06-23 2:00 ` [PATCH 01/11] spi-dw: expose platform data stucture dirk.brandewie
2011-06-23 3:47 ` Grant Likely
2011-06-23 4:00 ` Dirk Brandewie
2011-06-23 4:03 ` glikely@secretlab.ca
2011-06-23 4:37 ` Dirk Brandewie
2011-06-23 5:06 ` glikely@secretlab.ca
2011-06-23 5:16 ` Dirk Brandewie
2011-06-23 2:00 ` [PATCH 10/11] spi-dw: Move checking of max_speed_hz value to be a prerequisite in spi_dw_setup dirk.brandewie
[not found] ` <1308794413-11069-1-git-send-email-dirk.brandewie-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2011-06-23 2:00 ` [PATCH 02/11] spi-dw: update function naming convention to match file naming dirk.brandewie-Re5JQEeQqe8AvxtiuMwx3w
2011-06-23 2:00 ` [PATCH 03/11] spi-dw: change MRST prefix to generic prefix dirk.brandewie-Re5JQEeQqe8AvxtiuMwx3w
2011-06-23 2:00 ` [PATCH 04/11] spi-dw: remove unused definition dirk.brandewie-Re5JQEeQqe8AvxtiuMwx3w
2011-06-23 2:00 ` [PATCH 05/11] spi-dw: split spi_dw_enable_chip() into spi_dw_enable()/spi_dw_disable() dirk.brandewie-Re5JQEeQqe8AvxtiuMwx3w
2011-06-23 2:00 ` [PATCH 06/11] spi-dw: Force error on out of range chip select dirk.brandewie-Re5JQEeQqe8AvxtiuMwx3w
2011-06-23 3:51 ` Grant Likely
2011-06-23 4:13 ` Dirk Brandewie
2011-06-23 2:00 ` [PATCH 07/11] spi-dw: Set number of available chip selects correctly dirk.brandewie-Re5JQEeQqe8AvxtiuMwx3w
2011-06-23 3:53 ` Grant Likely
2011-06-23 2:00 ` [PATCH 08/11] spi-dw: Ensure fifo lenght is set dirk.brandewie-Re5JQEeQqe8AvxtiuMwx3w
2011-06-23 2:41 ` Feng Tang
2011-06-23 3:01 ` Dirk Brandewie
2011-06-23 3:21 ` Feng Tang
2011-06-23 3:55 ` Grant Likely
2011-06-23 4:20 ` Dirk Brandewie
2011-06-23 2:00 ` [PATCH 09/11] spi-dw: Fix condition in spi_dw_{writer/reader} dirk.brandewie-Re5JQEeQqe8AvxtiuMwx3w
2011-06-23 2:45 ` Feng Tang
2011-06-23 3:09 ` Dirk Brandewie
2011-06-23 3:25 ` Feng Tang [this message]
2011-06-23 3:30 ` Dirk Brandewie
2011-06-23 5:09 ` Feng Tang
2011-06-23 2:00 ` [PATCH 11/11] spi-dw: remove noop else clause dirk.brandewie-Re5JQEeQqe8AvxtiuMwx3w
2011-06-23 2:47 ` Feng Tang
2011-06-23 3:13 ` Dirk Brandewie
2011-06-23 2:39 ` [PATCH 00/11] RFC spi-dw updates Feng Tang
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