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From:   Ulf Hansson <ulf.hansson@linaro.org>
Date:   Fri, 17 Apr 2020 13:51:06 +0200
Message-ID: <CAPDyKFoVMBFTRJbEi-bjzeeMgi+z5xsBpBYteF=duCMb0Zxdhw@mail.gmail.com>
Subject: Re: [PATCH v2 0/2] amba/platform: Initialize dma_parms at the bus level
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Arnd Bergmann <arnd@arndb.de>,
        Linus Walleij <linus.walleij@linaro.org>
Cc:     Christoph Hellwig <hch@lst.de>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        "Rafael J . Wysocki" <rafael@kernel.org>,
        Russell King <linux@armlinux.org.uk>,
        Robin Murphy <robin.murphy@arm.com>,
        Vinod Koul <vkoul@kernel.org>, Haibo Chen <haibo.chen@nxp.com>,
        Ludovic Barre <ludovic.barre@st.com>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        dmaengine@vger.kernel.org
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 - Greg, Arnd, Linus, etc,

On Tue, 31 Mar 2020 at 20:38, Ulf Hansson <ulf.hansson@linaro.org> wrote:
>
> 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.
>
> 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              | 1 +
>  drivers/base/platform.c         | 2 ++
>  include/linux/amba/bus.h        | 1 +
>  include/linux/platform_device.h | 1 +
>  4 files changed, 5 insertions(+)
>
> --
> 2.20.1
>

Does this look okay or is there anything you would like me to change?

Kind regards
Uffe