Re: [PATCH v2 5/7] drm: rockchip: use common iommu api to attach iommu

[Shunqian Zheng <zhengsq-TNX95d0MmH7DzftRWevZcw@public.gmane.org>]

Hi,

On 2016年06月10日 16:03, Tomasz Figa wrote:
> Hi,
>
> On Wed, Jun 8, 2016 at 10:26 PM, Shunqian Zheng <zhengsq@rock-chips.com> wrote:
>> Rockchip DRM used the arm special API, arm_iommu_*(), to attach
>> iommu for ARM32 SoCs. This patch convert to common iommu API
>> so it would support ARM64 like RK3399.
>>
>> The general idea is domain_alloc(), attach_device() and
>> arch_setup_dma_ops() to set dma_ops manually for DRM at the last.
>>
>> Signed-off-by: Shunqian Zheng <zhengsq@rock-chips.com>
>> ---
>>   drivers/gpu/drm/rockchip/rockchip_drm_drv.c | 130 +++++++++++++++++++---------
>>   drivers/gpu/drm/rockchip/rockchip_drm_drv.h |   1 +
>>   2 files changed, 89 insertions(+), 42 deletions(-)
>>
> Please see my comments inline.
>
>> diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_drv.c b/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
>> index f5a68fc..7965a66 100644
>> --- a/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
>> +++ b/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
>> @@ -14,8 +14,6 @@
>>    * GNU General Public License for more details.
>>    */
>>
>> -#include <asm/dma-iommu.h>
>> -
>>   #include <drm/drmP.h>
>>   #include <drm/drm_crtc_helper.h>
>>   #include <drm/drm_fb_helper.h>
>> @@ -24,6 +22,8 @@
>>   #include <linux/module.h>
>>   #include <linux/of_graph.h>
>>   #include <linux/component.h>
>> +#include <linux/dma-iommu.h>
>> +#include <linux/iommu.h>
>>
>>   #include "rockchip_drm_drv.h"
>>   #include "rockchip_drm_fb.h"
>> @@ -46,7 +46,8 @@ static bool is_support_iommu = true;
>>   int rockchip_drm_dma_attach_device(struct drm_device *drm_dev,
>>                                     struct device *dev)
>>   {
>> -       struct dma_iommu_mapping *mapping = drm_dev->dev->archdata.mapping;
>> +       struct rockchip_drm_private *private = drm_dev->dev_private;
>> +       struct iommu_domain *domain = private->domain;
>>          int ret;
>>
>>          if (!is_support_iommu)
>> @@ -58,16 +59,25 @@ int rockchip_drm_dma_attach_device(struct drm_device *drm_dev,
>>
>>          dma_set_max_seg_size(dev, DMA_BIT_MASK(32));
>>
>> -       return arm_iommu_attach_device(dev, mapping);
>> +       ret = iommu_attach_device(domain, dev);
>> +
> nit: Unnecessary blank line.
Will fix it in v3.
>
>> +       if (ret) {
>> +               dev_err(dev, "Failed to attach iommu device\n");
>> +               return ret;
>> +       }
> nit: On the other hand, a blank line here would improve readability.
Will fix it in v3.
>
>> +       arch_setup_dma_ops(dev, 0x00000000, SZ_2G,
>> +                          (struct iommu_ops *)dev->bus->iommu_ops, false);
> This is casting a const pointer to a non-const pointer. which isn't
> really a good idea. I can see that arch_setup_dma_ops() requires a
> writable pointer, though. Looking at the implementations of
> arch_setup_dma_ops() around the platforms (namely arm and arm64...),
> it makes me wonder if the prototype shouldn't be changed to const
> instead.
Actually, kernel-next changed iommu_ops to const by:
53c92d7 iommu: of: enforce const-ness of struct iommu_ops

Will remove casting in the v3.
>
>> +       return 0;
>>   }
>>
>>   void rockchip_drm_dma_detach_device(struct drm_device *drm_dev,
>>                                      struct device *dev)
>>   {
>> -       if (!is_support_iommu)
>> -               return;
>> +       struct rockchip_drm_private *private = drm_dev->dev_private;
>> +       struct iommu_domain *domain = private->domain;
>>
>> -       arm_iommu_detach_device(dev);
>> +       if (is_support_iommu)
>> +               iommu_detach_device(domain, dev);
>>   }
>>
>>   int rockchip_register_crtc_funcs(struct drm_crtc *crtc,
>> @@ -132,10 +142,70 @@ static void rockchip_drm_crtc_disable_vblank(struct drm_device *dev,
>>                  priv->crtc_funcs[pipe]->disable_vblank(crtc);
>>   }
>>
>> +static int rockchip_drm_init_iommu(struct drm_device *drm_dev)
>> +{
>> +       struct rockchip_drm_private *private = drm_dev->dev_private;
>> +       struct device *dev = drm_dev->dev;
>> +       int ret;
>> +
>> +       dev->dma_parms = devm_kzalloc(dev, sizeof(*dev->dma_parms),
>> +                                     GFP_KERNEL);
>> +       if (!dev->dma_parms) {
>> +               ret = -ENOMEM;
>> +               return ret;
> nit: return -ENOMEM;
Will fix it in v3.
>
>> +       }
>> +
>> +       ret = dma_set_coherent_mask(dev, DMA_BIT_MASK(32));
>> +       if (ret) {
>> +               dev_err(dev, "Failed to set coherent mask\n");
>> +               return ret;
>> +       }
>> +
>> +       dma_set_max_seg_size(dev, DMA_BIT_MASK(32));
>> +
>> +       private->domain = iommu_domain_alloc(&platform_bus_type);
>> +       if (!private->domain)
>> +               return -ENOMEM;
>> +
>> +       ret = iommu_get_dma_cookie(private->domain);
>> +       if (ret) {
>> +               dev_err(dev, "Failed to get dma cookie\n");
>> +               goto err_free_domain;
>> +       }
>> +
>> +       ret = iommu_dma_init_domain(private->domain, 0x00000000, SZ_2G);
> I guess djkurtz's TODO comment could be preserved here.
Agree.

Thank you very much.
Shunqian
>
> Best regards,
> Tomasz
>
>
>


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