[PATCH v1 2/2] mmc: cavium: Remove redundant if-statement checkup

[PATCH v1 2/2] mmc: cavium: Remove redundant if-statement checkup

[Bean Huo]

From: Bean Huo <beanhuo@micron.com>

Currently, we have two ways to issue multiple-block read/write the
command to the eMMC. One is by normal IO request path fs->block->mmc.
Another one is that we can issue multiple-block read/write through
MMC ioctl interface. For the first path, mrq->stop, and mrq->stop->opcode
will be initialized in mmc_blk_data_prep(). However, for the second IO
path, mrq->stop is not initialized since it is a pre-defined multiple
blocks read/write.

Meanwhile, if it is open-ended multiple block read/write command,
STOP_TRANSMISSION CMD12 will be issued later in mmc_blk_issue_drv_op(),
since it is MMC_IOC_MULTI_CMD.

So, delete these if-statement checkups, let these kinds of multiple-block
read/write request go.

Fixes 'ba3869ff32e4 ("mmc: cavium: Add core MMC driver for Cavium SOCs")'
Cc: stable@vger.kernel.org
Signed-off-by: Bean Huo <beanhuo@micron.com>
---
 drivers/mmc/host/cavium.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/mmc/host/cavium.c b/drivers/mmc/host/cavium.c
index 95a41983c6c0..8fb7cbcf62ad 100644
--- a/drivers/mmc/host/cavium.c
+++ b/drivers/mmc/host/cavium.c
@@ -654,8 +654,7 @@ static void cvm_mmc_dma_request(struct mmc_host *mmc,
 	struct mmc_data *data;
 	u64 emm_dma, addr;
 
-	if (!mrq->data || !mrq->data->sg || !mrq->data->sg_len ||
-	    !mrq->stop || mrq->stop->opcode != MMC_STOP_TRANSMISSION) {
+	if (!mrq->data || !mrq->data->sg || !mrq->data->sg_len) {
 		dev_err(&mmc->card->dev, "Error: %s no data\n", __func__);
 		goto error;
 	}
-- 
2.25.1

Re: [PATCH v1 2/2] mmc: cavium: Remove redundant if-statement checkup

[Ulf Hansson]

On Fri, 19 Mar 2021 at 13:14, Bean Huo <huobean@gmail.com> wrote:
>
> From: Bean Huo <beanhuo@micron.com>
>
> Currently, we have two ways to issue multiple-block read/write the
> command to the eMMC. One is by normal IO request path fs->block->mmc.
> Another one is that we can issue multiple-block read/write through
> MMC ioctl interface. For the first path, mrq->stop, and mrq->stop->opcode
> will be initialized in mmc_blk_data_prep(). However, for the second IO
> path, mrq->stop is not initialized since it is a pre-defined multiple
> blocks read/write.

As a matter of fact this way is also supported for the regular block
I/O path. To make the mmc block driver to use it, mmc host drivers
need to announce that it's supported by setting MMC_CAP_CMD23.

It looks like that is what your patch should be targeted towards, can
you have a look at this instead?

Kind regards
Uffe

>
> Meanwhile, if it is open-ended multiple block read/write command,
> STOP_TRANSMISSION CMD12 will be issued later in mmc_blk_issue_drv_op(),
> since it is MMC_IOC_MULTI_CMD.
>
> So, delete these if-statement checkups, let these kinds of multiple-block
> read/write request go.
>
> Fixes 'ba3869ff32e4 ("mmc: cavium: Add core MMC driver for Cavium SOCs")'
> Cc: stable@vger.kernel.org
> Signed-off-by: Bean Huo <beanhuo@micron.com>
> ---
>  drivers/mmc/host/cavium.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/drivers/mmc/host/cavium.c b/drivers/mmc/host/cavium.c
> index 95a41983c6c0..8fb7cbcf62ad 100644
> --- a/drivers/mmc/host/cavium.c
> +++ b/drivers/mmc/host/cavium.c
> @@ -654,8 +654,7 @@ static void cvm_mmc_dma_request(struct mmc_host *mmc,
>         struct mmc_data *data;
>         u64 emm_dma, addr;
>
> -       if (!mrq->data || !mrq->data->sg || !mrq->data->sg_len ||
> -           !mrq->stop || mrq->stop->opcode != MMC_STOP_TRANSMISSION) {
> +       if (!mrq->data || !mrq->data->sg || !mrq->data->sg_len) {
>                 dev_err(&mmc->card->dev, "Error: %s no data\n", __func__);
>                 goto error;
>         }
> --
> 2.25.1
>

Re: [PATCH v1 2/2] mmc: cavium: Remove redundant if-statement checkup

[Bean Huo]

On Fri, 2021-03-19 at 15:09 +0100, Ulf Hansson wrote:
> On Fri, 19 Mar 2021 at 13:14, Bean Huo <huobean@gmail.com> wrote:
> 
> > From: Bean Huo <beanhuo@micron.com>
> > Currently, we have two ways to issue multiple-block read/write the
> > command to the eMMC. One is by normal IO request path fs->block-
> > >mmc.
> > Another one is that we can issue multiple-block read/write through
> > MMC ioctl interface. For the first path, mrq->stop, and mrq->stop-
> > >opcode
> > will be initialized in mmc_blk_data_prep(). However, for the second
> > IO
> > path, mrq->stop is not initialized since it is a pre-defined
> > multiple
> > blocks read/write.
> 
> 
> As a matter of fact this way is also supported for the regular block
> 
> I/O path. To make the mmc block driver to use it, mmc host drivers
> 
> need to announce that it's supported by setting MMC_CAP_CMD23.
> 
> 
> 
> It looks like that is what your patch should be targeted towards, can
> 
> you have a look at this instead?
> 
> 

Hi Ulf,
Thanks for your comments. I will look at that as your suggestion.
The patch [1/2] is accepted, so I will just update this patch to
the next version.

Kind regards,
Bean

> 
> Kind regards
> 
> Uffe

Re: [PATCH v1 2/2] mmc: cavium: Remove redundant if-statement checkup

[Bean Huo]

On Fri, 2021-03-19 at 16:42 +0100, Bean Huo wrote:
> On Fri, 2021-03-19 at 15:09 +0100, Ulf Hansson wrote:
> 
> > On Fri, 19 Mar 2021 at 13:14, Bean Huo <huobean@gmail.com> wrote:
> > > From: Bean Huo <beanhuo@micron.com>
> > > Currently, we have two ways to issue multiple-block read/write
> > > the
> > > command to the eMMC. One is by normal IO request path fs->block-
> > > > mmc.
> > > Another one is that we can issue multiple-block read/write
> > > through
> > > MMC ioctl interface. For the first path, mrq->stop, and mrq-
> > > >stop-
> > > > opcode
> > > will be initialized in mmc_blk_data_prep(). However, for the
> > > second
> > > IO
> > > path, mrq->stop is not initialized since it is a pre-defined
> > > multiple
> > > blocks read/write.
> > As a matter of fact this way is also supported for the regular
> > block
> > I/O path. To make the mmc block driver to use it, mmc host drivers
> > need to announce that it's supported by setting MMC_CAP_CMD23.
> > It looks like that is what your patch should be targeted towards,
> > can
> > you have a look at this instead?
> 
> 
> Hi Ulf,
> 
> Thanks for your comments. I will look at that as your suggestion.
> 
> The patch [1/2] is accepted, so I will just update this patch to
> 
> the next version.
> 
> 
> 
> Kind regards,
> 
> Bean


Hi Uffe,
Could you please firstly accept this patch? let the customer update
their kernel. As I tried to develop the next version of the patch
according to your suggestion, more changes will be involved. Also, no
matter how to make the change general, below mrq->stop checkup should
be deleted since it is obsolete. In the data transmission completion
interrupt, mrq->stop will be checked again.

-	if (!mrq->data || !mrq->data->sg || !mrq->data->sg_len ||
-	    !mrq->stop || mrq->stop->opcode != MMC_STOP_TRANSMISSION) {
+	if (!mrq->data || !mrq->data->sg || !mrq->data->sg_len) {


Kind regards
Bean

Re: [PATCH v1 2/2] mmc: cavium: Remove redundant if-statement checkup

[Ulf Hansson]

On Thu, 29 Apr 2021 at 22:30, Bean Huo <huobean@gmail.com> wrote:
>
> On Fri, 2021-03-19 at 16:42 +0100, Bean Huo wrote:
> > On Fri, 2021-03-19 at 15:09 +0100, Ulf Hansson wrote:
> >
> > > On Fri, 19 Mar 2021 at 13:14, Bean Huo <huobean@gmail.com> wrote:
> > > > From: Bean Huo <beanhuo@micron.com>
> > > > Currently, we have two ways to issue multiple-block read/write
> > > > the
> > > > command to the eMMC. One is by normal IO request path fs->block-
> > > > > mmc.
> > > > Another one is that we can issue multiple-block read/write
> > > > through
> > > > MMC ioctl interface. For the first path, mrq->stop, and mrq-
> > > > >stop-
> > > > > opcode
> > > > will be initialized in mmc_blk_data_prep(). However, for the
> > > > second
> > > > IO
> > > > path, mrq->stop is not initialized since it is a pre-defined
> > > > multiple
> > > > blocks read/write.
> > > As a matter of fact this way is also supported for the regular
> > > block
> > > I/O path. To make the mmc block driver to use it, mmc host drivers
> > > need to announce that it's supported by setting MMC_CAP_CMD23.
> > > It looks like that is what your patch should be targeted towards,
> > > can
> > > you have a look at this instead?
> >
> >
> > Hi Ulf,
> >
> > Thanks for your comments. I will look at that as your suggestion.
> >
> > The patch [1/2] is accepted, so I will just update this patch to
> >
> > the next version.
> >
> >
> >
> > Kind regards,
> >
> > Bean
>
>
> Hi Uffe,
> Could you please firstly accept this patch? let the customer update
> their kernel. As I tried to develop the next version of the patch
> according to your suggestion, more changes will be involved. Also, no
> matter how to make the change general, below mrq->stop checkup should
> be deleted since it is obsolete. In the data transmission completion
> interrupt, mrq->stop will be checked again.
>
> -       if (!mrq->data || !mrq->data->sg || !mrq->data->sg_len ||
> -           !mrq->stop || mrq->stop->opcode != MMC_STOP_TRANSMISSION) {
> +       if (!mrq->data || !mrq->data->sg || !mrq->data->sg_len) {
>

Well, I don't think the above checks are incorrect. Instead I think it
points out that the cavium mmc driver lacks support for CMD23, while
only open ended data transfers are supported.

The proper way forward is instead to implement CMD23 support to the
cavium mmc driver. In the same patch adding that support, you should
be able to remove the above checks.

Kind regards
Uffe