From: Robin Murphy <robin.murphy@arm.com>
To: Serge Semin <Sergey.Semin@baikalelectronics.ru>,
Gustavo Pimentel <gustavo.pimentel@synopsys.com>,
Vinod Koul <vkoul@kernel.org>, Jingoo Han <jingoohan1@gmail.com>,
Bjorn Helgaas <bhelgaas@google.com>, Frank Li <Frank.Li@nxp.com>,
Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>,
Christoph Hellwig <hch@lst.de>,
Marek Szyprowski <m.szyprowski@samsung.com>,
Vladimir Murzin <vladimir.murzin@arm.com>
Cc: "Serge Semin" <fancer.lancer@gmail.com>,
"Alexey Malahov" <Alexey.Malahov@baikalelectronics.ru>,
"Pavel Parkhomenko" <Pavel.Parkhomenko@baikalelectronics.ru>,
"Lorenzo Pieralisi" <lorenzo.pieralisi@arm.com>,
"Rob Herring" <robh@kernel.org>,
"Krzysztof Wilczyński" <kw@linux.com>,
linux-pci@vger.kernel.org, dmaengine@vger.kernel.org,
linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org
Subject: Re: [PATCH 03/25] dma-direct: take dma-ranges/offsets into account in resource mapping
Date: Thu, 24 Mar 2022 11:30:38 +0000 [thread overview]
Message-ID: <0baff803-b0ea-529f-095a-897398b4f63f@arm.com> (raw)
In-Reply-To: <20220324014836.19149-4-Sergey.Semin@baikalelectronics.ru>
On 2022-03-24 01:48, Serge Semin wrote:
> A basic device-specific linear memory mapping was introduced back in
> commit ("dma: Take into account dma_pfn_offset") as a single-valued offset
> preserved in the device.dma_pfn_offset field, which was initialized for
> instance by means of the "dma-ranges" DT property. Afterwards the
> functionality was extended to support more than one device-specific region
> defined in the device.dma_range_map list of maps. But all of these
> improvements concerned a single pointer, page or sg DMA-mapping methods,
> while the system resource mapping function turned to miss the
> corresponding modification. Thus the dma_direct_map_resource() method now
> just casts the CPU physical address to the device DMA address with no
> dma-ranges-based mapping taking into account, which is obviously wrong.
> Let's fix it by using the phys_to_dma_direct() method to get the
> device-specific bus address from the passed memory resource for the case
> of the directly mapped DMA.
It may not have been well-documented at the time, but this was largely
intentional. The assumption based on known systems was that where
dma_pfn_offset existed, it would *not* apply to peer MMIO addresses.
For instance, DTs for TI Keystone 2 platforms only describe an offset
for RAM:
dma-ranges = <0x80000000 0x8 0x00000000 0x80000000>;
but a DMA controller might also want to access something in the MMIO
range 0x0-0x7fffffff, of which it still has an identical non-offset
view. If a driver was previously using dma_map_resource() for that, it
would now start getting DMA_MAPPING_ERROR because the dma_range_map
exists but doesn't describe the MMIO region. I agree that in hindsight
it's not an ideal situation, but it's how things have ended up, so at
this point I'm wary of making potentially-breaking changes.
May I ask what exactly your setup looks like, if you have a DMA
controller with an offset view of its "own" MMIO space?
Thanks,
Robin.
> Fixes: 25f1e1887088 ("dma: Take into account dma_pfn_offset")
> Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
> ---
> kernel/dma/direct.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
> index 50f48e9e4598..9ce8192b29ab 100644
> --- a/kernel/dma/direct.c
> +++ b/kernel/dma/direct.c
> @@ -497,7 +497,7 @@ int dma_direct_map_sg(struct device *dev, struct scatterlist *sgl, int nents,
> dma_addr_t dma_direct_map_resource(struct device *dev, phys_addr_t paddr,
> size_t size, enum dma_data_direction dir, unsigned long attrs)
> {
> - dma_addr_t dma_addr = paddr;
> + dma_addr_t dma_addr = phys_to_dma_direct(dev, paddr);
>
> if (unlikely(!dma_capable(dev, dma_addr, size, false))) {
> dev_err_once(dev,
next prev parent reply other threads:[~2022-03-24 11:30 UTC|newest]
Thread overview: 79+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-24 1:48 [PATCH 00/25] dmaengine: dw-edma: Add RP/EP local DMA controllers support Serge Semin
2022-03-24 1:48 ` [PATCH 01/25] dmaengine: dw-edma: Drop dma_slave_config.direction field usage Serge Semin
2022-03-24 13:30 ` Manivannan Sadhasivam
2022-04-05 11:15 ` Serge Semin
2022-03-24 1:48 ` [PATCH 02/25] dmaengine: dw-edma: Fix eDMA Rd/Wr-channels and DMA-direction semantics Serge Semin
2022-03-24 1:48 ` [PATCH 03/25] dma-direct: take dma-ranges/offsets into account in resource mapping Serge Semin
2022-03-24 11:30 ` Robin Murphy [this message]
2022-04-17 22:44 ` Serge Semin
2022-04-20 7:12 ` Christoph Hellwig
2022-04-20 8:32 ` Serge Semin
2022-04-20 8:47 ` Christoph Hellwig
2022-04-20 8:55 ` Serge Semin
2022-04-21 14:45 ` Christoph Hellwig
2022-04-21 17:35 ` Serge Semin
2022-04-21 20:51 ` Robin Murphy
2022-04-24 21:46 ` Serge Semin
2022-03-24 1:48 ` [PATCH 04/25] dmaengine: Fix dma_slave_config.dst_addr description Serge Semin
2022-03-24 14:08 ` Manivannan Sadhasivam
2022-03-31 5:38 ` Vinod Koul
2022-03-31 7:13 ` Serge Semin
2022-03-31 10:50 ` Manivannan Sadhasivam
2022-03-24 1:48 ` [PATCH 05/25] dmaengine: dw-edma: Convert ll/dt phys-address to PCIe bus/DMA address Serge Semin
2022-03-24 16:23 ` Manivannan Sadhasivam
2022-03-24 1:48 ` [PATCH 06/25] dmaengine: dw-edma: Fix missing src/dst address of the interleaved xfers Serge Semin
2022-03-24 16:26 ` Manivannan Sadhasivam
2022-03-24 1:48 ` [PATCH 07/25] dmaengine: dw-edma: Don't permit non-inc " Serge Semin
2022-03-24 17:15 ` Manivannan Sadhasivam
2022-04-17 22:59 ` Serge Semin
2022-03-24 1:48 ` [PATCH 08/25] dmaengine: dw-edma: Fix invalid interleaved xfers semantics Serge Semin
2022-03-24 1:48 ` [PATCH 09/25] dmaengine: dw-edma: Add CPU to PCIe bus address translation Serge Semin
2022-03-24 17:25 ` Manivannan Sadhasivam
2022-03-24 1:48 ` [PATCH 10/25] dmaengine: dw-edma: Add PCIe bus address getter to the remote EP glue-driver Serge Semin
2022-03-24 17:41 ` Manivannan Sadhasivam
2022-03-24 1:48 ` [PATCH 11/25] dmaengine: dw-edma: Drop chancnt initialization Serge Semin
2022-03-24 17:42 ` Manivannan Sadhasivam
2022-03-24 1:48 ` [PATCH 12/25] dmaengine: dw-edma: Fix DebugFS reg entry type Serge Semin
2022-03-24 17:48 ` Manivannan Sadhasivam
2022-03-24 1:48 ` [PATCH 13/25] dmaengine: dw-edma: Stop checking debugfs_create_*() return value Serge Semin
2022-03-24 18:12 ` Manivannan Sadhasivam
2022-03-24 1:48 ` [PATCH 14/25] dmaengine: dw-edma: Add dw_edma prefix to the DebugFS nodes descriptor Serge Semin
2022-03-24 18:14 ` Manivannan Sadhasivam
2022-03-24 1:48 ` [PATCH 15/25] dmaengine: dw-edma: Convert DebugFS descs to being kz-allocated Serge Semin
2022-03-25 6:03 ` Manivannan Sadhasivam
2022-03-25 6:42 ` Manivannan Sadhasivam
2022-04-18 7:17 ` Serge Semin
2022-03-24 1:48 ` [PATCH 16/25] dmaengine: dw-edma: Simplify the DebugFS context CSRs init procedure Serge Semin
2022-03-25 6:27 ` Manivannan Sadhasivam
2022-03-25 6:31 ` Manivannan Sadhasivam
2022-04-18 8:23 ` Serge Semin
2022-03-24 1:48 ` [PATCH 17/25] dmaengine: dw-edma: Move eDMA data pointer to DebugFS node descriptor Serge Semin
2022-03-25 6:35 ` Manivannan Sadhasivam
2022-03-24 1:48 ` [PATCH 18/25] dmaengine: dw-edma: Join Write/Read channels into a single device Serge Semin
2022-03-25 7:34 ` Manivannan Sadhasivam
2022-03-24 1:48 ` [PATCH 19/25] dmaengine: dw-edma: Use DMA-engine device DebugFS subdirectory Serge Semin
2022-03-25 7:41 ` Manivannan Sadhasivam
2022-03-24 1:48 ` [PATCH 20/25] dmaengine: dw-edma: Use non-atomic io-64 methods Serge Semin
2022-03-25 8:28 ` Manivannan Sadhasivam
2022-04-18 11:37 ` Serge Semin
2022-03-24 1:48 ` [PATCH 21/25] dmaengine: dw-edma: Drop DT-region allocation Serge Semin
2022-03-25 8:33 ` Manivannan Sadhasivam
2022-03-24 1:48 ` [PATCH 22/25] dmaengine: dw-edma: Replace chip ID number with device name Serge Semin
2022-03-25 10:02 ` Manivannan Sadhasivam
2022-04-18 12:17 ` Serge Semin
2022-03-24 1:48 ` [PATCH 23/25] dmaengine: dw-edma: Bypass dma-ranges mapping for the local setup Serge Semin
2022-03-25 18:10 ` Manivannan Sadhasivam
2022-04-18 13:36 ` Serge Semin
2022-03-24 1:48 ` [PATCH 24/25] dmaengine: dw-edma: Skip cleanup procedure if no private data found Serge Semin
2022-03-25 18:15 ` Manivannan Sadhasivam
2022-04-18 13:48 ` Serge Semin
2022-04-23 14:45 ` Manivannan Sadhasivam
2022-03-24 1:48 ` [PATCH 25/25] PCI: dwc: Add DW eDMA engine support Serge Semin
2022-03-28 14:15 ` Manivannan Sadhasivam
2022-04-19 20:54 ` Serge Semin
2022-04-23 14:40 ` Manivannan Sadhasivam
2022-04-25 5:22 ` Manivannan Sadhasivam
2022-04-28 14:05 ` Serge Semin
2022-04-28 17:09 ` Manivannan Sadhasivam
2022-04-29 16:13 ` Serge Semin
2022-04-29 17:20 ` Manivannan Sadhasivam
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