From: Robin Murphy <robin.murphy@arm.com>
To: Brian Starkey <brian.starkey@arm.com>,
John Stultz <john.stultz@linaro.org>
Cc: lkml <linux-kernel@vger.kernel.org>,
Rob Herring <robh+dt@kernel.org>,
Sumit Semwal <sumit.semwal@linaro.org>,
"Andrew F. Davis" <afd@ti.com>,
Benjamin Gaignard <benjamin.gaignard@linaro.org>,
Liam Mark <lmark@codeaurora.org>,
Pratik Patel <pratikp@codeaurora.org>,
Laura Abbott <labbott@redhat.com>, Chenbo Feng <fengc@google.com>,
Alistair Strachan <astrachan@google.com>,
Sandeep Patil <sspatil@google.com>,
Hridya Valsaraju <hridya@google.com>,
Christoph Hellwig <hch@lst.de>,
Marek Szyprowski <m.szyprowski@samsung.com>,
Andrew Morton <akpm@linux-foundation.org>,
devicetree@vger.kernel.org, dri-devel@lists.freedesktop.org,
linux-mm@kvack.org, nd@arm.com
Subject: Re: [RFC][PATCH 3/4] dma-buf: cma_heap: Extend logic to export CMA regions tagged with "linux,cma-heap"
Date: Fri, 1 May 2020 12:08:48 +0100 [thread overview]
Message-ID: <47e7eded-7240-887a-39e1-97c55bf752e7@arm.com> (raw)
In-Reply-To: <20200501102143.xcckvsfecumbei3c@DESKTOP-E1NTVVP.localdomain>
On 2020-05-01 11:21 am, Brian Starkey wrote:
> Hi John,
>
> On Fri, May 01, 2020 at 07:39:48AM +0000, John Stultz wrote:
>> This patch reworks the cma_heap initialization so that
>> we expose both the default CMA region and any CMA regions
>> tagged with "linux,cma-heap" in the device-tree.
>>
>> Cc: Rob Herring <robh+dt@kernel.org>
>> Cc: Sumit Semwal <sumit.semwal@linaro.org>
>> Cc: "Andrew F. Davis" <afd@ti.com>
>> Cc: Benjamin Gaignard <benjamin.gaignard@linaro.org>
>> Cc: Liam Mark <lmark@codeaurora.org>
>> Cc: Pratik Patel <pratikp@codeaurora.org>
>> Cc: Laura Abbott <labbott@redhat.com>
>> Cc: Brian Starkey <Brian.Starkey@arm.com>
>> Cc: Chenbo Feng <fengc@google.com>
>> Cc: Alistair Strachan <astrachan@google.com>
>> Cc: Sandeep Patil <sspatil@google.com>
>> Cc: Hridya Valsaraju <hridya@google.com>
>> Cc: Christoph Hellwig <hch@lst.de>
>> Cc: Marek Szyprowski <m.szyprowski@samsung.com>
>> Cc: Robin Murphy <robin.murphy@arm.com>
>> Cc: Andrew Morton <akpm@linux-foundation.org>
>> Cc: devicetree@vger.kernel.org
>> Cc: dri-devel@lists.freedesktop.org
>> Cc: linux-mm@kvack.org
>> Signed-off-by: John Stultz <john.stultz@linaro.org>
>> ---
>> drivers/dma-buf/heaps/cma_heap.c | 18 +++++++++---------
>> 1 file changed, 9 insertions(+), 9 deletions(-)
>>
>> diff --git a/drivers/dma-buf/heaps/cma_heap.c b/drivers/dma-buf/heaps/cma_heap.c
>> index 626cf7fd033a..dd154e2db101 100644
>> --- a/drivers/dma-buf/heaps/cma_heap.c
>> +++ b/drivers/dma-buf/heaps/cma_heap.c
>> @@ -141,6 +141,11 @@ static int __add_cma_heap(struct cma *cma, void *data)
>> {
>> struct cma_heap *cma_heap;
>> struct dma_heap_export_info exp_info;
>> + struct cma *default_cma = dev_get_cma_area(NULL);
>> +
>> + /* We only add the default heap and explicitly tagged heaps */
>> + if (cma != default_cma && !cma_dma_heap_enabled(cma))
>> + return 0;
>
> Thinking about the pl111 thread[1], I'm wondering if we should also
> let drivers call this directly to expose their CMA pools, even if they
> aren't tagged for dma-heaps in DT. But perhaps that's too close to
> policy.
That sounds much like what my first thoughts were - apologies if I'm
wildly off-base here, but as far as I understand:
- Device drivers know whether they have their own "memory-region" or not.
- Device drivers already have to do *something* to participate in dma-buf.
- Device drivers know best how they make use of both the above.
- Therefore couldn't it be left to drivers to choose whether to register
their CMA regions as heaps, without having to mess with DT at all?
Robin.
>
> Cheers,
> -Brian
>
> [1] https://lists.freedesktop.org/archives/dri-devel/2020-April/264358.html
>
>>
>> cma_heap = kzalloc(sizeof(*cma_heap), GFP_KERNEL);
>> if (!cma_heap)
>> @@ -162,16 +167,11 @@ static int __add_cma_heap(struct cma *cma, void *data)
>> return 0;
>> }
>>
>> -static int add_default_cma_heap(void)
>> +static int cma_heaps_init(void)
>> {
>> - struct cma *default_cma = dev_get_cma_area(NULL);
>> - int ret = 0;
>> -
>> - if (default_cma)
>> - ret = __add_cma_heap(default_cma, NULL);
>> -
>> - return ret;
>> + cma_for_each_area(__add_cma_heap, NULL);
>> + return 0;
>> }
>> -module_init(add_default_cma_heap);
>> +module_init(cma_heaps_init);
>> MODULE_DESCRIPTION("DMA-BUF CMA Heap");
>> MODULE_LICENSE("GPL v2");
>> --
>> 2.17.1
>>
next prev parent reply other threads:[~2020-05-01 11:08 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-01 7:39 [RFC][PATCH 0/4] Support non-default CMA regions to the dmabuf heaps interface John Stultz
2020-05-01 7:39 ` [RFC][PATCH 1/4] devicetree: bindings: Add linux,cma-heap tag for reserved memory John Stultz
2020-05-01 10:42 ` Brian Starkey
2020-05-01 18:40 ` John Stultz
2020-05-04 8:50 ` Brian Starkey
2020-05-06 16:04 ` Andrew F. Davis
2020-05-06 16:30 ` John Stultz
2020-05-06 17:35 ` Andrew F. Davis
2020-05-06 18:34 ` John Stultz
2020-05-01 7:39 ` [RFC][PATCH 2/4] mm: cma: Add dma_heap flag to cma structure John Stultz
2020-05-01 10:48 ` Brian Starkey
2020-05-01 18:42 ` John Stultz
2020-05-01 7:39 ` [RFC][PATCH 3/4] dma-buf: cma_heap: Extend logic to export CMA regions tagged with "linux,cma-heap" John Stultz
2020-05-01 10:21 ` Brian Starkey
2020-05-01 11:08 ` Robin Murphy [this message]
2020-05-01 19:01 ` John Stultz
2020-05-04 9:06 ` Brian Starkey
2020-05-12 16:37 ` Rob Herring
2020-05-13 10:44 ` Brian Starkey
2020-05-14 14:52 ` Rob Herring
2020-05-15 9:32 ` Brian Starkey
2020-05-01 7:39 ` [RFC][PATCH 4/4] example: dts: hi3660-hikey960: Add dts entries to test cma heap binding John Stultz
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