From mboxrd@z Thu Jan 1 00:00:00 1970 From: Catalin Marinas Subject: Re: [PATCH 1/3] Honor ACPI _CCA attribute setting Date: Fri, 14 Aug 2015 14:14:28 +0100 Message-ID: <20150814131427.GD16368@e104818-lin.cambridge.arm.com> References: <1439416290-21228-1-git-send-email-jeremy.linton@arm.com> <1439416290-21228-2-git-send-email-jeremy.linton@arm.com> <55CD4832.7070301@amd.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <55CD4832.7070301-5C7GfCeVMHo@public.gmane.org> Sender: linux-usb-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Suravee Suthikulpanit Cc: Jeremy Linton , linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, rafael.j.wysocki-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org, Arnd Bergmann , linux-usb-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-ci5G2KO2hbZ+pU9mqzGVBQ@public.gmane.org, linux-acpi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, stern-nwvwT67g6+6dFdvTe/nMLpVzexx5G7lz@public.gmane.org List-Id: linux-acpi@vger.kernel.org On Fri, Aug 14, 2015 at 08:45:22AM +0700, Suravee Suthikulpanit wrote: > On 8/13/15 04:51, Jeremy Linton wrote: > >ACPI configurations can now mark devices as noncoherent, > >support that choice. > > > >Signed-off-by: Jeremy Linton > >--- > > include/acpi/acpi_bus.h | 5 +++-- > > 1 file changed, 3 insertions(+), 2 deletions(-) > > > >diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h > >index 83061ca..7ecb8e4 100644 > >--- a/include/acpi/acpi_bus.h > >+++ b/include/acpi/acpi_bus.h > >@@ -399,7 +399,7 @@ static inline bool acpi_check_dma(struct acpi_device *adev, bool *coherent) > > * case 1. Do not support and disable DMA. > > * case 2. Support but rely on arch-specific cache maintenance for > > * non-coherence DMA operations. > >- * Currently, we implement case 1 above. > >+ * Currently, we implement case 2 above. > > * > > * For the case when _CCA is missing (i.e. cca_seen=0) and > > * platform specifies ACPI_CCA_REQUIRED, we do not support DMA, > >@@ -407,7 +407,8 @@ static inline bool acpi_check_dma(struct acpi_device *adev, bool *coherent) > > * > > * See acpi_init_coherency() for more info. > > */ > >- if (adev->flags.coherent_dma) { > >+ if (adev->flags.coherent_dma || > >+ (adev->flags.cca_seen && IS_ENABLED(CONFIG_ARM64))) { > > ret = true; > > if (coherent) > > *coherent = adev->flags.coherent_dma; > > > > This change was in my earlier revisions for the original patch series to add > ACPI CCA support. At the time, this was pushed back since we were not sure > whether this would be a useful case, and whether such hardware exists. > > Would it be useful to document somewhere (may be in the GIT commit message) > about which hardware might need this? So far, it's the ARM Juno development board (the emphasis here is on being able to use it for development, not a production system). I think the commit log should also give you credit for the original implementation. > Arnd/Catalin, any feedback on this? That's where it was left in the previous thread: https://lkml.org/lkml/2015/5/21/376 (and I'll refrain from further comments ;)) -- Catalin -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html