Hi Miaoqian,
[email protected] wrote on Tue, 12 Apr 2022 16:23:24 +0800:
> Hi Miquel,
>
> On 2022/4/12 15:48, Miquel Raynal wrote:
> >
> >>> Hi Miaoqian,
> >>>
> >>> [email protected] wrote on Tue, 12 Apr 2022 06:36:52 +0000:
> >>>
> >>>> wait_for_completion_timeout() returns unsigned long not int.
> >>>> It returns 0 if timed out, and positive if completed.
> >>>> The check for <= 0 is ambiguous and should be == 0 here
> >>>> indicating timeout which is the only error case.
> >>>>
> >>>> Fixes: 83738d87e3a0 ("mtd: sh_flctl: Add DMA capabilty")
> >>>> Signed-off-by: Miaoqian Lin <[email protected]>
> >>>> ---
> >>>> change in v2:
> >>>> - initialize ret to 1.
> >>>> ---
> >>>> drivers/mtd/nand/raw/sh_flctl.c | 8 +++++---
> >>>> 1 file changed, 5 insertions(+), 3 deletions(-)
> >>>>
> >>>> diff --git a/drivers/mtd/nand/raw/sh_flctl.c b/drivers/mtd/nand/raw/sh_flctl.c
> >>>> index b85b9c6fcc42..2373251f585b 100644
> >>>> --- a/drivers/mtd/nand/raw/sh_flctl.c
> >>>> +++ b/drivers/mtd/nand/raw/sh_flctl.c
> >>>> @@ -384,7 +384,8 @@ static int flctl_dma_fifo0_transfer(struct sh_flctl *flctl, unsigned long *buf,
> >>>> dma_addr_t dma_addr;
> >>>> dma_cookie_t cookie;
> >>>> uint32_t reg;
> >>>> - int ret;
> >>>> + int ret = 1;
> >>> Does not look right. I know this function returns > 0 on positive
> >>> outcomes but this does not make any sense in the first place.
> >> Yes, I made a mistake, Now I realize that in v2, it will return 1 in error path
> >>
> >> when DMA submit failed.
> > Not 1, but a proper error code please (-ETIMEDOUT, -EINVAL, whatever)
> >
> >> And for patch v1, it will return 0 if calls wait_for_completion_timeout succeeds.
> >>
> >>> This function is static and only called twice, please turn it into
> >>> something like:
> >>>
> >>> if (dma_fifo_transfer())
> >>> error
> >>> else
> >>> ok
> >> So I want to keep ret>0 means success.
> >>
> >> Or could I set ret > 0 after in wait_for_completion_timeout() success path?
> >>
> >> like:
> >>
> >> if(time_left == 0)
> >>
> >> ret = -ETIMEDOUT;
> >>
> >> else
> >>
> >> ret = 1;
> > You can initialize ret to zero at to top. So that anything != 0 is an
> > error (like a lot of functions in the kernel).
>
> Thanks for your advice, I will do this.
> > And use:
> >
> > if (dma_fifo_transfer())
> > error();
> I think keeping the original condition structure is better,
> something like:
>
> if (dma_fifo_transfer()==0)
if (cond && cond && !dma_fifo_transfer())
> succeed();
>
> In this way, only minor changes is needed——only need to update the symbol in condition.
> Otherwise It needs to restructure the code and be more complicated.
>
>
> Thanks,
>
> >> What do you think?
> >>
> >>
> >> Thanks,
> >>
> >>>> + unsigned long time_left;
> >>>>
> >>>> if (dir == DMA_FROM_DEVICE) {
> >>>> chan = flctl->chan_fifo0_rx;
> >>>> @@ -425,13 +426,14 @@ static int flctl_dma_fifo0_transfer(struct sh_flctl *flctl, unsigned long *buf,
> >>>> goto out;
> >>>> }
> >>>>
> >>>> - ret =
> >>>> + time_left =
> >>>> wait_for_completion_timeout(&flctl->dma_complete,
> >>>> msecs_to_jiffies(3000));
> >>>>
> >>>> - if (ret <= 0) {
> >>>> + if (time_left == 0) {
> >>>> dmaengine_terminate_all(chan);
> >>>> dev_err(&flctl->pdev->dev, "wait_for_completion_timeout\n");
> >>>> + ret = -ETIMEDOUT;
> >>>> }
> >>>>
> >>>> out:
> >>> Thanks,
> >>> Miquèl
> >
> > Thanks,
> > Miquèl
Thanks,
Miquèl
wait_for_completion_timeout() returns unsigned long not int.
It returns 0 if timed out, and positive if completed.
The check for <= 0 is ambiguous and should be == 0 here
indicating timeout which is the only error case.
Fixes: 83738d87e3a0 ("mtd: sh_flctl: Add DMA capabilty")
Signed-off-by: Miaoqian Lin <[email protected]>
---
change in v2:
- initialize ret to 1.
---
changes in v3:
- initialize ret to 0, now ret==0 means success.
- update condition check in caller.
---
drivers/mtd/nand/raw/sh_flctl.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)
diff --git a/drivers/mtd/nand/raw/sh_flctl.c b/drivers/mtd/nand/raw/sh_flctl.c
index b85b9c6fcc42..a278829469d6 100644
--- a/drivers/mtd/nand/raw/sh_flctl.c
+++ b/drivers/mtd/nand/raw/sh_flctl.c
@@ -384,7 +384,8 @@ static int flctl_dma_fifo0_transfer(struct sh_flctl *flctl, unsigned long *buf,
dma_addr_t dma_addr;
dma_cookie_t cookie;
uint32_t reg;
- int ret;
+ int ret = 0;
+ unsigned long time_left;
if (dir == DMA_FROM_DEVICE) {
chan = flctl->chan_fifo0_rx;
@@ -425,13 +426,14 @@ static int flctl_dma_fifo0_transfer(struct sh_flctl *flctl, unsigned long *buf,
goto out;
}
- ret =
+ time_left =
wait_for_completion_timeout(&flctl->dma_complete,
msecs_to_jiffies(3000));
- if (ret <= 0) {
+ if (time_left == 0) {
dmaengine_terminate_all(chan);
dev_err(&flctl->pdev->dev, "wait_for_completion_timeout\n");
+ ret = -ETIMEDOUT;
}
out:
@@ -441,7 +443,7 @@ static int flctl_dma_fifo0_transfer(struct sh_flctl *flctl, unsigned long *buf,
dma_unmap_single(chan->device->dev, dma_addr, len, dir);
- /* ret > 0 is success */
+ /* ret == 0 is success */
return ret;
}
@@ -465,7 +467,7 @@ static void read_fiforeg(struct sh_flctl *flctl, int rlen, int offset)
/* initiate DMA transfer */
if (flctl->chan_fifo0_rx && rlen >= 32 &&
- flctl_dma_fifo0_transfer(flctl, buf, rlen, DMA_FROM_DEVICE) > 0)
+ !flctl_dma_fifo0_transfer(flctl, buf, rlen, DMA_FROM_DEVICE))
goto convert; /* DMA success */
/* do polling transfer */
@@ -524,7 +526,7 @@ static void write_ec_fiforeg(struct sh_flctl *flctl, int rlen,
/* initiate DMA transfer */
if (flctl->chan_fifo0_tx && rlen >= 32 &&
- flctl_dma_fifo0_transfer(flctl, buf, rlen, DMA_TO_DEVICE) > 0)
+ !flctl_dma_fifo0_transfer(flctl, buf, rlen, DMA_TO_DEVICE))
return; /* DMA success */
/* do polling transfer */
--
2.17.1
On Tue, 2022-04-12 at 08:34:31 UTC, Miaoqian Lin wrote:
> wait_for_completion_timeout() returns unsigned long not int.
> It returns 0 if timed out, and positive if completed.
> The check for <= 0 is ambiguous and should be == 0 here
> indicating timeout which is the only error case.
>
> Fixes: 83738d87e3a0 ("mtd: sh_flctl: Add DMA capabilty")
> Signed-off-by: Miaoqian Lin <[email protected]>
Applied to https://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux.git mtd/fixes, thanks.
Miquel