| Message ID | 3525869e8e7530128bf9718ae8af7d7564b3c684.1532382222.git.robin.murphy@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Stop losing firmware-set DMA masks | expand |
On Mon, Jul 23, 2018 at 11:16:11PM +0100, Robin Murphy wrote: > Now that we can track upstream DMA constraints properly with > bus_dma_mask instead of trying (and failing) to maintain it in > coherent_dma_mask, it doesn't make much sense for the firmware code to > be touching the latter at all. It's merely papering over bugs wherein a > driver has failed to call dma_set_coherent_mask() *and* the bus code has > not initialised any default value. Nit: I do not think the driver had a chance to probe and therefore call dma_set_coherent_mask() before iort_dma_setup() is executed, right ? Anyway, the patch makes perfect sense: Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> > We don't really want to encourage more drivers coercing dma_mask so > we'll continue to fix that up if necessary, but add a warning to help > flush out any such buggy bus code that remains. > > CC: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> > CC: Hanjun Guo <hanjun.guo@linaro.org> > CC: Sudeep Holla <sudeep.holla@arm.com> > Signed-off-by: Robin Murphy <robin.murphy@arm.com> > --- > drivers/acpi/arm64/iort.c | 22 +++++++++++----------- > 1 file changed, 11 insertions(+), 11 deletions(-) > > diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c > index bc51cff5505e..08f26db2da7e 100644 > --- a/drivers/acpi/arm64/iort.c > +++ b/drivers/acpi/arm64/iort.c > @@ -978,20 +978,20 @@ void iort_dma_setup(struct device *dev, u64 *dma_addr, u64 *dma_size) > int ret, msb; > > /* > - * Set default coherent_dma_mask to 32 bit. Drivers are expected to > - * setup the correct supported mask. > + * If @dev is expected to be DMA-capable then the bus code that created > + * it should have initialised its dma_mask pointer by this point. For > + * now, we'll continue the legacy behaviour of coercing it to the > + * coherent mask if not, but we'll no longer do so quietly. > */ > - if (!dev->coherent_dma_mask) > - dev->coherent_dma_mask = DMA_BIT_MASK(32); > - > - /* > - * Set it to coherent_dma_mask by default if the architecture > - * code has not set it. > - */ > - if (!dev->dma_mask) > + if (!dev->dma_mask) { > + dev_warn(dev, "DMA mask not set\n"); > dev->dma_mask = &dev->coherent_dma_mask; > + } > > - size = max(dev->coherent_dma_mask, dev->coherent_dma_mask + 1); > + if (dev->coherent_dma_mask) > + size = max(dev->coherent_dma_mask, dev->coherent_dma_mask + 1); > + else > + size = 1ULL << 32; > > if (dev_is_pci(dev)) { > ret = acpi_dma_get_range(dev, &dmaaddr, &offset, &size); > -- > 2.17.1.dirty >
On 2018-07-25 4:27 PM, Lorenzo Pieralisi wrote: > On Mon, Jul 23, 2018 at 11:16:11PM +0100, Robin Murphy wrote: >> Now that we can track upstream DMA constraints properly with >> bus_dma_mask instead of trying (and failing) to maintain it in >> coherent_dma_mask, it doesn't make much sense for the firmware code to >> be touching the latter at all. It's merely papering over bugs wherein a >> driver has failed to call dma_set_coherent_mask() *and* the bus code has >> not initialised any default value. > > Nit: I do not think the driver had a chance to probe and therefore call > dma_set_coherent_mask() before iort_dma_setup() is executed, right ? Indeed, dma_configure() should be invoked shortly before the driver's .probe() routine, so at this point the struct device has only been touched by the bus code which created it. Anyone managing to call it on a device which already has a driver bound is doing something horribly wrong. > Anyway, the patch makes perfect sense: > > Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Thanks, Robin. >> We don't really want to encourage more drivers coercing dma_mask so >> we'll continue to fix that up if necessary, but add a warning to help >> flush out any such buggy bus code that remains. >> >> CC: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> >> CC: Hanjun Guo <hanjun.guo@linaro.org> >> CC: Sudeep Holla <sudeep.holla@arm.com> >> Signed-off-by: Robin Murphy <robin.murphy@arm.com> >> --- >> drivers/acpi/arm64/iort.c | 22 +++++++++++----------- >> 1 file changed, 11 insertions(+), 11 deletions(-) >> >> diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c >> index bc51cff5505e..08f26db2da7e 100644 >> --- a/drivers/acpi/arm64/iort.c >> +++ b/drivers/acpi/arm64/iort.c >> @@ -978,20 +978,20 @@ void iort_dma_setup(struct device *dev, u64 *dma_addr, u64 *dma_size) >> int ret, msb; >> >> /* >> - * Set default coherent_dma_mask to 32 bit. Drivers are expected to >> - * setup the correct supported mask. >> + * If @dev is expected to be DMA-capable then the bus code that created >> + * it should have initialised its dma_mask pointer by this point. For >> + * now, we'll continue the legacy behaviour of coercing it to the >> + * coherent mask if not, but we'll no longer do so quietly. >> */ >> - if (!dev->coherent_dma_mask) >> - dev->coherent_dma_mask = DMA_BIT_MASK(32); >> - >> - /* >> - * Set it to coherent_dma_mask by default if the architecture >> - * code has not set it. >> - */ >> - if (!dev->dma_mask) >> + if (!dev->dma_mask) { >> + dev_warn(dev, "DMA mask not set\n"); >> dev->dma_mask = &dev->coherent_dma_mask; >> + } >> >> - size = max(dev->coherent_dma_mask, dev->coherent_dma_mask + 1); >> + if (dev->coherent_dma_mask) >> + size = max(dev->coherent_dma_mask, dev->coherent_dma_mask + 1); >> + else >> + size = 1ULL << 32; >> >> if (dev_is_pci(dev)) { >> ret = acpi_dma_get_range(dev, &dmaaddr, &offset, &size); >> -- >> 2.17.1.dirty >>
diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c index bc51cff5505e..08f26db2da7e 100644 --- a/drivers/acpi/arm64/iort.c +++ b/drivers/acpi/arm64/iort.c @@ -978,20 +978,20 @@ void iort_dma_setup(struct device *dev, u64 *dma_addr, u64 *dma_size) int ret, msb; /* - * Set default coherent_dma_mask to 32 bit. Drivers are expected to - * setup the correct supported mask. + * If @dev is expected to be DMA-capable then the bus code that created + * it should have initialised its dma_mask pointer by this point. For + * now, we'll continue the legacy behaviour of coercing it to the + * coherent mask if not, but we'll no longer do so quietly. */ - if (!dev->coherent_dma_mask) - dev->coherent_dma_mask = DMA_BIT_MASK(32); - - /* - * Set it to coherent_dma_mask by default if the architecture - * code has not set it. - */ - if (!dev->dma_mask) + if (!dev->dma_mask) { + dev_warn(dev, "DMA mask not set\n"); dev->dma_mask = &dev->coherent_dma_mask; + } - size = max(dev->coherent_dma_mask, dev->coherent_dma_mask + 1); + if (dev->coherent_dma_mask) + size = max(dev->coherent_dma_mask, dev->coherent_dma_mask + 1); + else + size = 1ULL << 32; if (dev_is_pci(dev)) { ret = acpi_dma_get_range(dev, &dmaaddr, &offset, &size);
Now that we can track upstream DMA constraints properly with bus_dma_mask instead of trying (and failing) to maintain it in coherent_dma_mask, it doesn't make much sense for the firmware code to be touching the latter at all. It's merely papering over bugs wherein a driver has failed to call dma_set_coherent_mask() *and* the bus code has not initialised any default value. We don't really want to encourage more drivers coercing dma_mask so we'll continue to fix that up if necessary, but add a warning to help flush out any such buggy bus code that remains. CC: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> CC: Hanjun Guo <hanjun.guo@linaro.org> CC: Sudeep Holla <sudeep.holla@arm.com> Signed-off-by: Robin Murphy <robin.murphy@arm.com> --- drivers/acpi/arm64/iort.c | 22 +++++++++++----------- 1 file changed, 11 insertions(+), 11 deletions(-)