Hi Marek,
On Mon, Mar 30, 2026 at 07:49:26PM +0200, Marek Szyprowski wrote:
> On 30.03.2026 17:40, Maxime Ripard wrote:
> > Commit 3a236f6a5cf2 ("dma: contiguous: Turn heap registration logic
> > around") didn't remove one last call to dma_heap_cma_register_heap()
> > that it removed, thus breaking the build.
> >
> > That last call is in dma_contiguous_reserve(), to handle the
> > registration of the default CMA region heap instance.
> >
> > The default CMA region instance is already somewhat handled by
> > retrieving it through the dev_get_cma_area() call in the CMA heap
> > driver. However, since commit 854acbe75ff4 ("dma-buf: heaps: Give
> > default CMA heap a fixed name"), we will create two heap instances for
> > the CMA default region.
> >
> > The first one is always called "default_cma_region", and is the one
> > handled by the call to dev_get_cma_area() mentioned earlier. The second
> > one is the name it used to have prior to that last commit for backward
> > compatibility.
> >
> > In the case where the default CMA region is defined in the DT, then that
> > region is registered through rmem_cma_setup() and that region is added
> > to the list of CMA regions to create a CMA heap instance for.
> >
> > In the case where the default CMA region is not defined in the DT
> > though used to be the case covered by the now removed
> > dma_heap_cma_register_heap() in dma_contiguous_reserve(). If we only
> > remove the call to dma_heap_cma_register_heap(), then the legacy name of
> > the CMA heap will not be registered anymore. We thus need to replace
> > that call with a call to rmem_cma_insert_area() to make sure we queue
> > this instance, if created, to create a heap instance.
> >
> > Once that call to dma_heap_cma_register_heap() replaced, we can also
> > remove the now unused function definition, its now empty header, and all
> > includes of this header.
> >
> > Fixes: 3a236f6a5cf2 ("dma: contiguous: Turn heap registration logic around")
> > Reported-by: Mark Brown <[email protected]>
> > Closes: https://lore.kernel.org/linux-next/[email protected]/
> > Signed-off-by: Maxime Ripard <[email protected]>
> > ---
> > Changes in v2:
> > - Fix creation of the CMA heap instance with the legacy name when not
> > declared in the DT.
> > - Link to v1:
> > https://lore.kernel.org/r/[email protected]
> > ---
> > drivers/dma-buf/heaps/cma_heap.c | 1 -
> > include/linux/dma-buf/heaps/cma.h | 16 ----------------
> > kernel/dma/contiguous.c | 14 +++++++++++---
> > 3 files changed, 11 insertions(+), 20 deletions(-)
> >
> > diff --git a/drivers/dma-buf/heaps/cma_heap.c
> > b/drivers/dma-buf/heaps/cma_heap.c
> > index
> > 7216a14262b04bb6130ddf26b7d009f7d15b03fd..9a8b36bc929f6daa483a0139a2919d95127e0d23
> > 100644
> > --- a/drivers/dma-buf/heaps/cma_heap.c
> > +++ b/drivers/dma-buf/heaps/cma_heap.c
> > @@ -12,11 +12,10 @@
> >
> > #define pr_fmt(fmt) "cma_heap: " fmt
> >
> > #include <linux/cma.h>
> > #include <linux/dma-buf.h>
> > -#include <linux/dma-buf/heaps/cma.h>
> > #include <linux/dma-heap.h>
> > #include <linux/dma-map-ops.h>
> > #include <linux/err.h>
> > #include <linux/highmem.h>
> > #include <linux/io.h>
> > diff --git a/include/linux/dma-buf/heaps/cma.h
> > b/include/linux/dma-buf/heaps/cma.h
> > deleted file mode 100644
> > index
> > e751479e21e703e24a5f799b4a7fc8bd0df3c1c4..0000000000000000000000000000000000000000
> > --- a/include/linux/dma-buf/heaps/cma.h
> > +++ /dev/null
> > @@ -1,16 +0,0 @@
> > -/* SPDX-License-Identifier: GPL-2.0 */
> > -#ifndef DMA_BUF_HEAP_CMA_H_
> > -#define DMA_BUF_HEAP_CMA_H_
> > -
> > -struct cma;
> > -
> > -#ifdef CONFIG_DMABUF_HEAPS_CMA
> > -int dma_heap_cma_register_heap(struct cma *cma);
> > -#else
> > -static inline int dma_heap_cma_register_heap(struct cma *cma)
> > -{
> > - return 0;
> > -}
> > -#endif // CONFIG_DMABUF_HEAPS_CMA
> > -
> > -#endif // DMA_BUF_HEAP_CMA_H_
> > diff --git a/kernel/dma/contiguous.c b/kernel/dma/contiguous.c
> > index
> > ad50512d71d3088a73e4b1ac02d6e6122374888e..d5d15983060c5c54744d6a63f2b591e1a3455b86
> > 100644
> > --- a/kernel/dma/contiguous.c
> > +++ b/kernel/dma/contiguous.c
> > @@ -40,11 +40,10 @@
> > #include <asm/page.h>
> >
> > #include <linux/memblock.h>
> > #include <linux/err.h>
> > #include <linux/sizes.h>
> > -#include <linux/dma-buf/heaps/cma.h>
> > #include <linux/dma-map-ops.h>
> > #include <linux/cma.h>
> > #include <linux/nospec.h>
> >
> > #ifdef CONFIG_CMA_SIZE_MBYTES
> > @@ -217,10 +216,19 @@ static void __init dma_numa_cma_reserve(void)
> > static inline void __init dma_numa_cma_reserve(void)
> > {
> > }
> > #endif
> >
> > +#ifdef CONFIG_OF_RESERVED_MEM
> > +static int rmem_cma_insert_area(struct cma *cma);
> > +#else
> > +static inline int rmem_cma_insert_area(struct cma *cma)
> > +{
> > + return 0;
> > +}
> > +#endif
> > +
> > /**
> > * dma_contiguous_reserve() - reserve area(s) for contiguous memory
> > handling
> > * @limit: End address of the reserved memory (optional, 0 for any).
> > *
> > * This function reserves memory from early allocator. It should be
> > @@ -271,13 +279,13 @@ void __init dma_contiguous_reserve(phys_addr_t limit)
> > &dma_contiguous_default_area,
> > fixed);
> > if (ret)
> > return;
> >
> > - ret = dma_heap_cma_register_heap(dma_contiguous_default_area);
> > + ret = rmem_cma_insert_area(dma_contiguous_default_area);
> > if (ret)
> > - pr_warn("Couldn't register default CMA heap.");
> > + pr_warn("Couldn't queue default CMA region for heap
> > creation.");
> > }
> > }
> >
> > void __weak
> > dma_contiguous_early_fixup(phys_addr_t base, unsigned long size)
> >
> > ---
>
> Huh, this is still not the correct fix to restore the old behavior.
> When !CONFIG_OF_RESERVED_MEM the default cma area should be still
> registered as the default cma dma-buf heap.You're right, but it feels that it's a fundamental flaw in the original patch rather than a quick fix for the build now. Can you drop the patches you applied entirely? If so, I'll send a new version of that series. Maxime
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