linux-kernel - Re: [PATCH v2 5/5] ACPI/IORT: Add IORT named component memory address limits

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Message-ID: <833cf8e7-8dc5-49c6-2beb-4683af354b6d@linaro.org>
Date:   Tue, 1 Aug 2017 20:56:39 +0800
From:   Hanjun Guo <hanjun.guo@...aro.org>
To:     Lorenzo Pieralisi <lorenzo.pieralisi@....com>
Cc:     linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        Will Deacon <will.deacon@....com>,
        Robin Murphy <robin.murphy@....com>,
        Nate Watterson <nwatters@...eaurora.org>,
        Robert Moore <robert.moore@...el.com>, Feng Kan <fkan@....com>,
        Jon Masters <jcm@...hat.com>, Zhang Rui <rui.zhang@...el.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>
Subject: Re: [PATCH v2 5/5] ACPI/IORT: Add IORT named component memory address
 limits

On 2017/8/1 19:21, Lorenzo Pieralisi wrote:
> On Tue, Aug 01, 2017 at 06:20:43PM +0800, Hanjun Guo wrote:
>> Hi Lorenzo,
>>
>> On 2017/7/31 23:23, Lorenzo Pieralisi wrote:
>>> IORT named components provide firmware configuration describing
>>> how many address bits a given device is capable of generating
>>> to address memory.
>>>
>>> Add code to the kernel to retrieve memory address limits
>>> configuration for IORT named components and configure DMA masks
>>> accordingly.
>>>
>>> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
>>> Cc: Will Deacon <will.deacon@....com>
>>> Cc: Robin Murphy <robin.murphy@....com>
>>> Cc: Nate Watterson <nwatters@...eaurora.org>
>>> ---
>>>   drivers/acpi/arm64/iort.c | 40 ++++++++++++++++++++++++++++++----------
>>>   1 file changed, 30 insertions(+), 10 deletions(-)
>>>
>>> diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
>>> index 67b85ae..b85d19f 100644
>>> --- a/drivers/acpi/arm64/iort.c
>>> +++ b/drivers/acpi/arm64/iort.c
>>> @@ -680,6 +680,24 @@ static const struct iommu_ops *iort_iommu_xlate(struct device *dev,
>>>   	return ret ? NULL : ops;
>>>   }
>>> +static int nc_dma_get_range(struct device *dev, u64 *size)
>>> +{
>>> +	struct acpi_iort_node *node;
>>> +	struct acpi_iort_named_component *ncomp;
>>> +
>>> +	node = iort_scan_node(ACPI_IORT_NODE_NAMED_COMPONENT,
>>> +			      iort_match_node_callback, dev);
>>> +	if (!node)
>>> +		return -ENODEV;
>>> +
>>> +	ncomp = (struct acpi_iort_named_component *)node->node_data;
>>> +
>>> +	*size = ncomp->memory_address_limit >= 64 ? ~0ULL :
>>> +			1ULL<<ncomp->memory_address_limit;
>>
>> Just a question here, if the IORT table didn't configure this
>> value properly, will the device working properly? I'm asking this
>> because in the table of IORT of D05, this value is set to 0 so far
>> (SAS and network), but I can boot D05 OK with your patch set, not
>> sure if any further issues.
> 
> Then you wonder why I wrote it as a separate patch. Why is that
> value set to 0 (is that because that's the insane default ?) ?
> It is a firmware bug and if things work ok with this patch applied
> either this patch contains a bug or drivers override the DMA masks
> to cancel out this patch effects.

Thanks for the reply, not a bug for this patch, I confirmed that
the driver override the DMA masks (both SAS and network set 64 bit
DMA mask).

> 
> Please fix the firmware.

Sure.

Thanks
Hanjun