On Thu, Mar 27, 2025 at 2:53 AM Rob Herring <r...@kernel.org> wrote:
>
> On Wed, Mar 26, 2025 at 1:44 AM Chen-Yu Tsai <w...@kernel.org> wrote:
> >
> > Hi,
> >
> > On Tue, Mar 18, 2025 at 7:29 AM Rob Herring (Arm) <r...@kernel.org> wrote:
> > >
> > > Simplify of_dma_set_restricted_buffer() by using of_property_present()
> > > and of_for_each_phandle() iterator.
> > >
> > > Signed-off-by: Rob Herring (Arm) <r...@kernel.org>
> > > ---
> > > drivers/of/device.c | 34 +++++++++++++---------------------
> > > 1 file changed, 13 insertions(+), 21 deletions(-)
> > >
> > > diff --git a/drivers/of/device.c b/drivers/of/device.c
> > > index edf3be197265..bb4a47d58249 100644
> > > --- a/drivers/of/device.c
> > > +++ b/drivers/of/device.c
> > > @@ -35,44 +35,36 @@ EXPORT_SYMBOL(of_match_device);
> > > static void
> > > of_dma_set_restricted_buffer(struct device *dev, struct device_node *np)
> > > {
> > > - struct device_node *node, *of_node = dev->of_node;
> > > - int count, i;
> > > + struct device_node *of_node = dev->of_node;
> > > + struct of_phandle_iterator it;
> > > + int rc, i = 0;
> > >
> > > if (!IS_ENABLED(CONFIG_DMA_RESTRICTED_POOL))
> > > return;
> > >
> > > - count = of_property_count_elems_of_size(of_node, "memory-region",
> > > - sizeof(u32));
> > > /*
> > > * If dev->of_node doesn't exist or doesn't contain
> > > memory-region, try
> > > * the OF node having DMA configuration.
> > > */
> > > - if (count <= 0) {
> > > + if (!of_property_present(of_node, "memory-region"))
> > > of_node = np;
> > > - count = of_property_count_elems_of_size(
> > > - of_node, "memory-region", sizeof(u32));
> > > - }
> > >
> > > - for (i = 0; i < count; i++) {
> > > - node = of_parse_phandle(of_node, "memory-region", i);
> > > + of_for_each_phandle(&it, rc, of_node, "memory-region", NULL, 0) {
> > > /*
> > > * There might be multiple memory regions, but only one
> > > * restricted-dma-pool region is allowed.
> > > */
> > > - if (of_device_is_compatible(node, "restricted-dma-pool")
> > > &&
> > > - of_device_is_available(node)) {
> > > - of_node_put(node);
> > > - break;
> > > + if (of_device_is_compatible(it.node,
> > > "restricted-dma-pool") &&
> > > + of_device_is_available(it.node)) {
> > > + if (!of_reserved_mem_device_init_by_idx(dev,
> > > of_node, i)) {
> > > + of_node_put(it.node);
> > > + return;
> > > + }
> > > }
> > > - of_node_put(node);
> > > + i++;
> > > }
> > >
> > > - /*
> > > - * Attempt to initialize a restricted-dma-pool region if one was
> > > found.
> > > - * Note that count can hold a negative error code.
> > > - */
> > > - if (i < count && of_reserved_mem_device_init_by_idx(dev, of_node,
> > > i))
> > > - dev_warn(dev, "failed to initialise
> > > \"restricted-dma-pool\" memory node\n");
> > > + dev_warn(dev, "failed to initialise \"restricted-dma-pool\"
> > > memory node\n");
> >
> > This changes the behavior. Before this patch, it was:
> >
> > if a restricted dma pool was found, but initializing it failed, print
> > a warning.
> >
> > Whereas now it has become:
> >
> > print a warning unless a restricted dma pool was found and successfully
> > initialized.
> >
> > This change causes the kernel to print out the warning for devices that
> > don't even do DMA:
>
> Thanks. I fixed it up to only warn if i is non-zero.
Not sure if that matches the old behavior though? A node could have
memory-regions for shared dma pools but not restricted dma pools,
and i would be non-zero.
IMO the warning should be in the "else" branch of
if (!of_reserved_mem_device_init_by_idx(dev, of_node, i))
ChenYu
