linux-kernel - Re: [PATCH 01/12] drm/ttm: Use ttm_bo_default_io_mem_pfn if io_mem

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Date:   Sun, 24 Dec 2017 10:27:02 +0100
From:   Christian König <ckoenig.leichtzumerken@...il.com>
To:     Tan Xiaojun <tanxiaojun@...wei.com>, seanpaul@...omium.org,
        christian.koenig@....com, airlied@...ux.ie, michel.daenzer@....com,
        alexander.deucher@....com, nicolai.haehnle@....com,
        thomas.lendacky@....com, yamada.masahiro@...ionext.com,
        msrb@...e.com, Felix.Kuehling@....com, dave.jiang@...el.com,
        gregkh@...uxfoundation.org, michael.thayer@...cle.com,
        hdegoede@...hat.com
Cc:     daniel.vetter@...el.com, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 01/12] drm/ttm: Use ttm_bo_default_io_mem_pfn if
 io_mem_pfn is NULL

Am 24.12.2017 um 07:14 schrieb Tan Xiaojun:
> From: Michal Srb <msrb@...e.com>
>
> The io_mem_pfn field was added in commit ea642c3216cb2a60d1c0e760ae47ee85c9c16447
> and is called unconditionally. However, not all drivers were updated to set it.
>
> Use the ttm_bo_default_io_mem_pfn function if a driver did not set its own.
>
> Signed-off-by: Michal Srb <msrb@...e.com>
> ---
>   drivers/gpu/drm/ttm/ttm_bo_vm.c | 5 ++++-
>   1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
> index c8ebb75..e25a99b 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
> @@ -234,7 +234,10 @@ static int ttm_bo_vm_fault(struct vm_fault *vmf)
>   		if (bo->mem.bus.is_iomem) {
>   			/* Iomem should not be marked encrypted */
>   			cvma.vm_page_prot = pgprot_decrypted(cvma.vm_page_prot);
> -			pfn = bdev->driver->io_mem_pfn(bo, page_offset);
> +			if (bdev->driver->io_mem_pfn)
> +				pfn = bdev->driver->io_mem_pfn(bo, page_offset);
> +			else
> +				pfn = ttm_bo_default_io_mem_pfn(bo, page_offset);

Please move this check into a new function ttm_bo_io_mem_pfn().

You can then move the calculation of ttm_bo_default_io_mem_pfn() into 
this new function in patch #12 as well.

Regards,
Christian.

>   		} else {
>   			page = ttm->pages[page_offset];
>   			if (unlikely(!page && i == 0)) {