From: Christoffer Dall <christoffer.dall@linaro.org>
To: Sinan Kaya <okaya@codeaurora.org>
Cc: dmaengine@vger.kernel.org, marc.zyngier@arm.com,
mark.rutland@arm.com, timur@codeaurora.org,
devicetree@vger.kernel.org, cov@codeaurora.org,
vinod.koul@intel.com, jcm@redhat.com, vikrams@codeaurora.org,
arnd@arndb.de, eric.auger@linaro.org,
linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, agross@codeaurora.org,
shankerd@codeaurora.org
Subject: Re: [PATCH V14 0/9] dma: add Qualcomm Technologies HIDMA driver
Date: Mon, 8 Feb 2016 18:00:26 +0100 [thread overview]
Message-ID: <20160208170026.GA23324@cbox> (raw)
In-Reply-To: <56B8A527.7010206@codeaurora.org>
On Mon, Feb 08, 2016 at 09:24:39AM -0500, Sinan Kaya wrote:
> Hi,
>
> On 2/8/2016 5:14 AM, Christoffer Dall wrote:
> > Hi Sinan,
> >
> > On Thu, Feb 04, 2016 at 11:34:31PM -0500, Sinan Kaya wrote:
> >> The Qualcomm Technologies HIDMA device has been designed
> >> to support virtualization technology. The driver has been
> >> divided into two to follow the hardware design.
> >>
> >> 1. HIDMA Management driver
> >> 2. HIDMA Channel driver
> >>
> >> Each HIDMA HW consists of multiple channels. These channels
> >> share some set of common parameters. These parameters are
> >> initialized by the management driver during power up.
> >> Same management driver is used for monitoring the execution
> >> of the channels. Management driver can change the performance
> >> behavior dynamically such as bandwidth allocation and
> >> prioritization in the future.
> >>
> >> The management driver is executed in host context and
> >> is the main management entity for all channels provided by
> >> the device.
> >
> > I'm not at all familiar with this kind of hardware.
> >
>
> Let me help.
>
> > Once an entity (userspace or VM) has a HIDAM channel assigned via VFIO,
> > how does it use it?
>
> HIDMA is a HW accelerator for memory operations like memcpy and memset. It fits
> into the DMA engine framework.
>
> There are two classes of DMA HW. These are slave DMA and standalone DMA. Slave DMA
> is generally related to another piece of HW that needs DMA for moving data.
> Standalone DMA is intended for OS/CPU consumption not HW. These can be used to offload
> crypto operations (XOR) or other memory transactions (memcpy and memset) that are
> lengthy.
>
> Once the HIDMA channel is assigned to the guest machine, guest operating system uses the
> DMA channel to offload memory operations as HIDMA only supports memcpy.
>
> IOMMU HW provides the isolation from the rest of the host kernel or from other guest machines.
>
> > Is it used in relation with another device to
> > perform DMA on its behalf or is a HIDMA channel something that's useful
> > on its own?
>
> It is standalone only. The relationship you are referring to is known as slave DMA engine.
> HIDMA does not support slave DMA. HIDMA only supports memcpy and memset in HW and only memcpy in SW
> as the memset support has been removed from the kernel long time ago.
>
Thanks for the explanation.
-Christoffer
next prev parent reply other threads:[~2016-02-08 16:59 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-05 4:34 [PATCH V14 0/9] dma: add Qualcomm Technologies HIDMA driver Sinan Kaya
2016-02-05 4:34 ` [PATCH V14 1/9] dma: qcom_bam_dma: move to qcom directory Sinan Kaya
2016-03-11 2:13 ` Vinod Koul
2016-02-05 4:34 ` [PATCH V14 2/9] dma: hidma: Add Device Tree binding Sinan Kaya
2016-03-11 2:16 ` Vinod Koul
2016-02-05 4:34 ` [PATCH V14 3/9] dma: add Qualcomm Technologies HIDMA management driver Sinan Kaya
2016-03-11 2:16 ` Vinod Koul
2016-02-05 4:34 ` [PATCH V14 4/9] dma: add Qualcomm Technologies HIDMA channel driver Sinan Kaya
2016-03-11 2:17 ` Vinod Koul
2016-02-05 4:34 ` [PATCH V14 5/9] dma: qcom_hidma: implement lower level hardware interface Sinan Kaya
2016-03-11 2:06 ` Vinod Koul
2016-03-11 3:08 ` Okaya
2016-03-11 16:02 ` Sinan Kaya
2016-03-11 16:32 ` Vinod Koul
2016-03-11 16:44 ` Sinan Kaya
2016-03-11 19:29 ` Sinan Kaya
2016-03-11 21:59 ` Sinan Kaya
2016-03-13 16:00 ` Vinod Koul
2016-03-14 13:53 ` Sinan Kaya
2016-03-13 15:59 ` Vinod Koul
2016-03-14 13:56 ` Sinan Kaya
2016-02-05 4:34 ` [PATCH V14 6/9] dma: qcom_hidma: add debugfs hooks Sinan Kaya
2016-02-05 4:34 ` [PATCH V14 7/9] dma: qcom_hidma: add support for object hierarchy Sinan Kaya
2016-02-05 4:34 ` [PATCH V14 8/9] vfio, platform: add support for ACPI while detecting the reset driver Sinan Kaya
2016-02-26 16:24 ` Sinan Kaya
2016-02-26 17:15 ` Eric Auger
2016-02-26 19:21 ` Sinan Kaya
2016-03-02 18:34 ` Sinan Kaya
2016-03-03 23:14 ` Eric Auger
2016-03-04 5:20 ` Sinan Kaya
2016-03-07 4:09 ` Eric Auger
2016-03-07 15:30 ` Sinan Kaya
2016-03-08 4:46 ` Eric Auger
2016-03-08 5:07 ` Sinan Kaya
2016-03-08 15:44 ` Sinan Kaya
2016-02-05 4:34 ` [PATCH V14 9/9] vfio, platform: add QTI HIDMA " Sinan Kaya
2016-02-26 17:52 ` Eric Auger
2016-02-26 19:05 ` Sinan Kaya
2016-02-08 10:14 ` [PATCH V14 0/9] dma: add Qualcomm Technologies HIDMA driver Christoffer Dall
2016-02-08 14:24 ` Sinan Kaya
2016-02-08 17:00 ` Christoffer Dall [this message]
2016-02-26 16:21 ` Sinan Kaya
2016-02-26 16:52 ` Timur Tabi
2016-03-02 18:40 ` Sinan Kaya
2016-03-03 3:44 ` Vinod Koul
2016-03-03 15:22 ` Sinan Kaya
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