Re: [PATCH v2] of/device: Update dma_range_map only when dev has valid dma-ranges

From: Robin Murphy <robin.murphy@arm.com>
To: Rob Herring <robh+dt@kernel.org>,
	Frank Rowand <frowand.list@gmail.com>,
	Christoph Hellwig <hch@lst.de>,
	Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Joerg Roedel <joro@8bytes.org>,
	Matthias Brugger <matthias.bgg@gmail.com>,
	Will Deacon <will@kernel.org>,
	Krzysztof Kozlowski <krzk@kernel.org>,
	Tomasz Figa <tfiga@google.com>,
	linux-mediatek@lists.infradead.org, srv_heupstream@mediatek.com,
	devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	iommu@lists.linux-foundation.org,
	Nicolas Boichat <drinkcat@chromium.org>,
	Yong Wu <yong.wu@mediatek.com>,
	Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Subject: Re: [PATCH v2] of/device: Update dma_range_map only when dev has valid dma-ranges
Date: Wed, 27 Jan 2021 13:13:22 +0000	[thread overview]
Message-ID: <159d4486-bb7e-249d-2bad-f5bba839041d@arm.com> (raw)
In-Reply-To: <YBFj9whLvqlV2erm@aptenodytes>

[ + Christoph, Marek ]

On 2021-01-27 13:00, Paul Kocialkowski wrote:
> Hi,
> 
> On Tue 19 Jan 21, 18:52, Yong Wu wrote:
>> The commit e0d072782c73 ("dma-mapping: introduce DMA range map,
>> supplanting dma_pfn_offset") always update dma_range_map even though it was
>> already set, like in the sunxi_mbus driver. the issue is reported at [1].
>> This patch avoid this(Updating it only when dev has valid dma-ranges).
>>
>> Meanwhile, dma_range_map contains the devices' dma_ranges information,
>> This patch moves dma_range_map before of_iommu_configure. The iommu
>> driver may need to know the dma_address requirements of its iommu
>> consumer devices.
> 
> Just a gentle ping on this issue, it would be nice to have this fix merged
> ASAP, in the next RC :)

Ack to that - Rob, Frank, do you want to take this through the OF tree, 
or shall we take it through the DMA-mapping tree like the original culprit?

Thanks,
Robin.

> 
> Cheers,
> 
> Paul
> 
>> [1] https://lore.kernel.org/linux-arm-kernel/5c7946f3-b56e-da00-a750-be097c7ceb32@arm.com/
>>
>> CC: Rob Herring <robh+dt@kernel.org>
>> CC: Frank Rowand <frowand.list@gmail.com>
>> Fixes: e0d072782c73 ("dma-mapping: introduce DMA range map, supplanting dma_pfn_offset"),
>> Suggested-by: Robin Murphy <robin.murphy@arm.com>
>> Signed-off-by: Yong Wu <yong.wu@mediatek.com>
>> Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
>> Reviewed-by: Rob Herring <robh@kernel.org>
>> ---
>>   drivers/of/device.c | 10 +++++++---
>>   1 file changed, 7 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/of/device.c b/drivers/of/device.c
>> index aedfaaafd3e7..1122daa8e273 100644
>> --- a/drivers/of/device.c
>> +++ b/drivers/of/device.c
>> @@ -162,9 +162,11 @@ int of_dma_configure_id(struct device *dev, struct device_node *np,
>>   	mask = DMA_BIT_MASK(ilog2(end) + 1);
>>   	dev->coherent_dma_mask &= mask;
>>   	*dev->dma_mask &= mask;
>> -	/* ...but only set bus limit if we found valid dma-ranges earlier */
>> -	if (!ret)
>> +	/* ...but only set bus limit and range map if we found valid dma-ranges earlier */
>> +	if (!ret) {
>>   		dev->bus_dma_limit = end;
>> +		dev->dma_range_map = map;
>> +	}
>>   
>>   	coherent = of_dma_is_coherent(np);
>>   	dev_dbg(dev, "device is%sdma coherent\n",
>> @@ -172,6 +174,9 @@ int of_dma_configure_id(struct device *dev, struct device_node *np,
>>   
>>   	iommu = of_iommu_configure(dev, np, id);
>>   	if (PTR_ERR(iommu) == -EPROBE_DEFER) {
>> +		/* Don't touch range map if it wasn't set from a valid dma-ranges */
>> +		if (!ret)
>> +			dev->dma_range_map = NULL;
>>   		kfree(map);
>>   		return -EPROBE_DEFER;
>>   	}
>> @@ -181,7 +186,6 @@ int of_dma_configure_id(struct device *dev, struct device_node *np,
>>   
>>   	arch_setup_dma_ops(dev, dma_start, size, iommu, coherent);
>>   
>> -	dev->dma_range_map = map;
>>   	return 0;
>>   }
>>   EXPORT_SYMBOL_GPL(of_dma_configure_id);
>> -- 
>> 2.18.0
>>
> 