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Subject: Re: [PATCH] gpu: host1x: fix compile error when IOMMU API is not
 available
To:     Thierry Reding <thierry.reding@gmail.com>,
        Ben Dooks <ben.dooks@codethink.co.uk>
Cc:     linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
        linux-tegra@vger.kernel.org, digetx@gmail.com,
        linux-tegra-owner@vger.kernel.org
References: <4c3d021c73c001f633803e364cfbc6ace3381205.1554936354.git.stefan@agner.ch>
 <7371b1573ddd0b127713724ef5051a6f@codethink.co.uk>
 <20190411083017.GB4633@ulmo>
From:   Mikko Perttunen <cyndis@kapsi.fi>
Message-ID: <c73bb650-7175-150b-a678-c707e5f0e7e7@kapsi.fi>
Date:   Thu, 11 Apr 2019 13:06:28 +0300
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On 11.4.2019 11.30, Thierry Reding wrote:
> On Thu, Apr 11, 2019 at 09:23:13AM +0100, Ben Dooks wrote:
>>
>>
>> On 2019-04-10 23:47, Stefan Agner wrote:
>>> In case the IOMMU API is not available compiling host1x fails with
>>> the following error:
>>>    In file included from drivers/gpu/host1x/hw/host1x06.c:27:
>>>    drivers/gpu/host1x/hw/channel_hw.c: In function
>>> ‘host1x_channel_set_streamid’:
>>>    drivers/gpu/host1x/hw/channel_hw.c:118:30: error: implicit
>>> declaration of function
>>>      ‘dev_iommu_fwspec_get’; did you mean ‘iommu_fwspec_free’?
>>> [-Werror=implicit-function-declaration]
>>>    struct iommu_fwspec *spec =
>>> dev_iommu_fwspec_get(channel->dev->parent);
>>>                                ^~~~~~~~~~~~~~~~~~~~
>>>                                iommu_fwspec_free
>>>
>>> Fixes: de5469c21ff9 ("gpu: host1x: Program the channel stream ID")
>>> Signed-off-by: Stefan Agner <stefan@agner.ch>
>>
>> would it be better to provide something like this i nthe header that
>> defines dev_iommu_fwspec_get() to be:
>>
>> static inline struct iommu_fwspec *dev_iommu_fwspec_get(struct device *dev)
>> { return NULL; }
>>
>> although returning an PTR_ERR would have been better.
> 
> I don't think there's really a large number of failures here. Either
> your device has an IOMMU fwspec or it doesn't.
> 
> But yes, I think it'd be better to have the above static inline dummy in
> iommu.h, but I'll apply this for now in the hopes of getting it in
> before v5.1 final.

A similar patch was already sent before by someone. That one also 
programs the bypass stream ID (0x7f) even if IOMMU is disabled. We 
should pick that patch instead.

Thanks,
Mikko

> 
> Thierry >
>>
>>> ---
>>>   drivers/gpu/host1x/hw/channel_hw.c | 2 +-
>>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/gpu/host1x/hw/channel_hw.c
>>> b/drivers/gpu/host1x/hw/channel_hw.c
>>> index 27101c04a827..4030d64916f0 100644
>>> --- a/drivers/gpu/host1x/hw/channel_hw.c
>>> +++ b/drivers/gpu/host1x/hw/channel_hw.c
>>> @@ -114,7 +114,7 @@ static inline void synchronize_syncpt_base(struct
>>> host1x_job *job)
>>>
>>>   static void host1x_channel_set_streamid(struct host1x_channel *channel)
>>>   {
>>> -#if HOST1X_HW >= 6
>>> +#if IS_ENABLED(CONFIG_IOMMU_API) &&  HOST1X_HW >= 6
>>>   	struct iommu_fwspec *spec =
>>> dev_iommu_fwspec_get(channel->dev->parent);
>>>   	u32 sid = spec ? spec->ids[0] & 0xffff : 0x7f;
>>>
>>> _______________________________________________
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>>> dri-devel@lists.freedesktop.org
>>> https://lists.freedesktop.org/mailman/listinfo/dri-devel