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From: Arnd Bergmann <arnd@kernel.org>
To: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Cc: DTML <devicetree@vger.kernel.org>,
	Florian Fainelli <f.fainelli@gmail.com>,
	Arnd Bergmann <arnd@arndb.de>,
	Neil Armstrong <narmstrong@baylibre.com>,
	David Woodhouse <dwmw2@infradead.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Russell King - ARM Linux <linux@armlinux.org.uk>,
	Christoph Hellwig <hch@infradead.org>,
	Will Deacon <will@kernel.org>, Rob Herring <robh+dt@kernel.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Robin Murphy <robin.murphy@arm.com>,
	Ard Biesheuvel <ardb@kernel.org>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [RFC 13/13] scsi: megaraid: Make use of dev_64bit_mmio_supported()
Date: Fri, 26 Feb 2021 19:06:43 +0100
Message-ID: <CAK8P3a03BcXZu+On885GaR547SHJYtiu3d_QHG0zOr2UiKn6qQ@mail.gmail.com> (raw)
In-Reply-To: <CAK8P3a1cDgSo7LTtBZpzBo3xu23_uDEux8=15Xyw6JTpXtGqhw@mail.gmail.com>

On Fri, Feb 26, 2021 at 3:30 PM Arnd Bergmann <arnd@kernel.org> wrote:
>
> On Fri, Feb 26, 2021 at 3:03 PM Nicolas Saenz Julienne
> <nsaenzjulienne@suse.de> wrote:
>
> >         unsigned long flags;
> > -       spin_lock_irqsave(&instance->hba_lock, flags);
> > -       writel(le32_to_cpu(req_desc->u.low),
> > -               &instance->reg_set->inbound_low_queue_port);
> > -       writel(le32_to_cpu(req_desc->u.high),
> > -               &instance->reg_set->inbound_high_queue_port);
> > -       spin_unlock_irqrestore(&instance->hba_lock, flags);
>
> > +
> > +       if (dev_64bit_mmio_supported(&instance->pdev->dev)) {
> > +               writeq(req_data, &instance->reg_set->inbound_low_queue_port);
> > +       } else {
> > +               spin_lock_irqsave(&instance->hba_lock, flags);
> > +               lo_hi_writeq(req_data, &instance->reg_set->inbound_low_queue_port);
> > +               spin_unlock_irqrestore(&instance->hba_lock, flags);
> > +       }
>
> I see your patch changes the code to the lo_hi_writeq() accessor,
> and it also fixes the endianness bug (double byteswap on big-endian),
> but it does not fix the spinlock bug (writel on pci leaks out of the lock
> unless it's followed by a read).

On second look, it seems your patch breaks the byteorder logic,
rather than fixing it. It would seem better to leave it unchanged
then, or to send a separate rework of the endianness conversion if
you think it is wrong.

       Arnd

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Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-26 14:02 [RFC 00/13] Generic way of dealing with broken 64-bit buses Nicolas Saenz Julienne
2021-02-26 14:02 ` [RFC 01/13] dt-bindings: Introduce 64bit-mmio-broken Nicolas Saenz Julienne
2021-02-26 14:02 ` [RFC 02/13] driver core: Introduce MMIO configuration Nicolas Saenz Julienne
2021-03-02 11:29   ` Robin Murphy
2021-03-02 14:09     ` Nicolas Saenz Julienne
2021-02-26 14:02 ` [RFC 03/13] of: device: Introduce of_mmio_configure() Nicolas Saenz Julienne
2021-02-26 14:02 ` [RFC 04/13] driver core: plafrom: Introduce platform_mmio_configure() Nicolas Saenz Julienne
2021-02-26 14:02 ` [RFC 05/13] pci: Introduce pci_mmio_configure() Nicolas Saenz Julienne
2021-02-26 14:02 ` [RFC 06/13] device core: Introduce dev_64bit_mmio_supported() Nicolas Saenz Julienne
2021-02-26 14:02 ` [RFC 07/13] arm64: Mark ARCH_MVEBU as needing broken 64bit MMIO support Nicolas Saenz Julienne
2021-02-26 14:03 ` [RFC 08/13] arm64: dts: marvell: armada-ap80x: Mark config-space bus as 64bit-mmio-broken Nicolas Saenz Julienne
2021-02-26 14:03 ` [RFC 09/13] iommu/arm-smmu: Make use of dev_64bit_mmio_supported() Nicolas Saenz Julienne
2021-03-02  9:32   ` Arnd Bergmann
2021-03-02 12:42     ` Nicolas Saenz Julienne
2021-03-02 11:07   ` Robin Murphy
2021-03-02 13:38     ` Nicolas Saenz Julienne
2021-03-03  8:44     ` Arnd Bergmann
2021-02-26 14:03 ` [RFC 10/13] iommu/arm-smmu-impl: Get rid of Marvell's implementation details Nicolas Saenz Julienne
2021-03-02 11:40   ` Robin Murphy
2021-03-02 14:06     ` Nicolas Saenz Julienne
2021-02-26 14:03 ` [RFC 11/13] arm64: Mark ARCH_BCM2835 as needing broken 64bit MMIO support Nicolas Saenz Julienne
2021-02-26 14:03 ` [RFC 12/13] ARM: dts: bcm2711: Mark PCIe bus as 64bit-mmio-broken Nicolas Saenz Julienne
2021-02-26 14:03 ` [RFC 13/13] scsi: megaraid: Make use of dev_64bit_mmio_supported() Nicolas Saenz Julienne
2021-02-26 14:30   ` Arnd Bergmann
2021-02-26 18:06     ` Arnd Bergmann [this message]

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