Re: [PATCH 0/2] amba/platform: Initialize dma_parms at the bus level

[Ulf Hansson]

On Fri, 27 Mar 2020 at 04:02, BOUGH CHEN <haibo.chen@xxxxxxx> wrote:
>
>
> > -----Original Message-----
> > From: BOUGH CHEN
> > Sent: 2020å3æ26æ 12:41
> > To: Ulf Hansson <ulf.hansson@xxxxxxxxxx>; Greg Kroah-Hartman
> > <gregkh@xxxxxxxxxxxxxxxxxxx>; Rafael J . Wysocki <rafael@xxxxxxxxxx>;
> > linux-kernel@xxxxxxxxxxxxxxx
> > Cc: Arnd Bergmann <arnd@xxxxxxxx>; Christoph Hellwig <hch@xxxxxx>;
> > Russell King <linux@xxxxxxxxxxxxxxx>; Linus Walleij <linus.walleij@xxxxxxxxxx>;
> > Vinod Koul <vkoul@xxxxxxxxxx>; Ludovic Barre <ludovic.barre@xxxxxx>;
> > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; dmaengine@xxxxxxxxxxxxxxx
> > Subject: RE: [PATCH 0/2] amba/platform: Initialize dma_parms at the bus level
> >
> > > -----Original Message-----
> > > From: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
> > > Sent: 2020å3æ25æ 19:34
> > > To: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>; Rafael J .
> > > Wysocki <rafael@xxxxxxxxxx>; linux-kernel@xxxxxxxxxxxxxxx
> > > Cc: Arnd Bergmann <arnd@xxxxxxxx>; Christoph Hellwig <hch@xxxxxx>;
> > > Russell King <linux@xxxxxxxxxxxxxxx>; Linus Walleij
> > > <linus.walleij@xxxxxxxxxx>; Vinod Koul <vkoul@xxxxxxxxxx>; BOUGH CHEN
> > > <haibo.chen@xxxxxxx>; Ludovic Barre <ludovic.barre@xxxxxx>;
> > > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; dmaengine@xxxxxxxxxxxxxxx; Ulf
> > > Hansson <ulf.hansson@xxxxxxxxxx>
> > > Subject: [PATCH 0/2] amba/platform: Initialize dma_parms at the bus
> > > level
> > >
> > > It's currently the amba/platform driver's responsibility to initialize
> > > the pointer, dma_parms, for its corresponding struct device. The
> > > benefit with this approach allows us to avoid the initialization and
> > > to not waste memory for the struct device_dma_parameters, as this can
> > > be decided on a case by case basis.
> > >
> > > However, it has turned out that this approach is not very practical.
> > > Not only does it lead to open coding, but also to real errors. In
> > > principle callers of
> > > dma_set_max_seg_size() doesn't check the error code, but just assumes
> > > it succeeds.
> > >
> > > For these reasons, this series initializes the dma_parms from the
> > > amba/platform bus at the device registration point. This also follows
> > > the way the PCI devices are being managed, see pci_device_add().
> > >
> > > If it turns out that this is an acceptable solution, we probably also
> > > want the changes for stable, but I am not sure if it applies without conflicts.
> > >
> > > The series is based on v5.6-rc7.
> > >
> >
> > Hi Ulf,
> >
> > Since i.MXQM SMMU related code still not upstream yet, so I apply your
> > patches on our internal Linux branch based on v5.4.24, and find it do not work
> > on my side. Maybe for platform core drivers, there is a gap between v5.4.24
> > and v5.6-rc7 which has the impact.
> > I will try to put our SMMU related code into v5.6-rc7, then do the test again.
> >
> >
>
> Hi Ulf,
>
> On the latest Linux-next branch, the top commit 89295c59c1f063b533d071ca49d0fa0c0783ca6f (tag: next-20200326), after add your two patches, I just add the simple debug code as following in the /driver/mmc/core/queue.c, but seems still not work as our expect, logically, it should work, so can you or anyone test on other platform? This seems weird.

You are right, this doesn't work for platform devices being added
through the OF path.

In other words, of_platform_device_create_pdata() manually allocates
the platform device and assigns it the &platform_bus_type, but without
calling platform_device_add().

For amba, it works fine, as in that OF path, amba_device_add() is called. Hmm.

I re-spin this, to address the problem. Perhaps we simply need to use
the ->probe() path.

Kind regards
Uffe

>
> diff --git a/drivers/mmc/core/queue.c b/drivers/mmc/core/queue.c
> index 25bee3daf9e2..f091280f7ffb 100644
> --- a/drivers/mmc/core/queue.c
> +++ b/drivers/mmc/core/queue.c
> @@ -403,6 +403,13 @@ static void mmc_setup_queue(struct mmc_queue *mq, struct mmc_card *card)
>                 blk_queue_max_segment_size(mq->queue,
>                         round_down(host->max_seg_size, block_size));
>
> +       pr_err("###### the max segment size is %d\n", queue_max_segment_size(mq->queue));
> +       if (host->parent->dma_parms) {
> +                      pr_err("######### the dma parms has value\n");
> +       } else if (!(host->parent->dma_parms)) {
> +                      pr_err("######## the dma parms is zero!!\n");
> +       }
> +
>         dma_set_max_seg_size(mmc_dev(host), queue_max_segment_size(mq->queue));
>
>         INIT_WORK(&mq->recovery_work, mmc_mq_recovery_handler);
>
> Here is the log I got when system run, even after your patch, the dev->dma_parms is still NULL.
> [    0.989853] mmc0: new HS400 MMC card at address 0001
> [    0.995708] sdhci-esdhc-imx 30b50000.mmc: Got CD GPIO
> [    0.999374] ###### the max segment size is 65024
> [    1.008594] ######## the dma parms is zero!!
> [    1.012875] mmcblk0: mmc0:0001 IB2932 29.2 GiB
> [    1.017569] ###### the max segment size is 65024
> [    1.022195] ######## the dma parms is zero!!
> [    1.026479] mmcblk0boot0: mmc0:0001 IB2932 partition 1 4.00 MiB
> [    1.032541] ###### the max segment size is 65024
> [    1.035198] mmc1: SDHCI controller on 30b50000.mmc [30b50000.mmc] using ADMA
> [    1.037169] ######## the dma parms is zero!!
> [    1.048493] mmcblk0boot1: mmc0:0001 IB2932 partition 2 4.00 MiB
> [    1.054531] mmcblk0rpmb: mmc0:0001 IB2932 partition 3 4.00 MiB, chardev (234:0)
>
>
> Regards
> Haibo Chen
> > Best Regards
> > Haibo Chen
> >
> > > Kind regards
> > > Ulf Hansson
> > >
> > > Ulf Hansson (2):
> > >   driver core: platform: Initialize dma_parms for platform devices
> > >   amba: Initialize dma_parms for amba devices
> > >
> > >  drivers/amba/bus.c              | 2 ++
> > >  drivers/base/platform.c         | 1 +
> > >  include/linux/amba/bus.h        | 1 +
> > >  include/linux/platform_device.h | 1 +
> > >  4 files changed, 5 insertions(+)
> > >
> > > --
> > > 2.20.1
>