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| From: | Makarov, Andrey |
| Subject: | Re: [PATCH v2] Align Raspberry Pi DMA interrupts with Linux DTS |
| Date: | Thu, 14 Jul 2022 10:33:23 +0000 |
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Hi Phil,
Agreed, for v3 I selected naming with "orgated" instead of "shared" because there is already IRQ line #15 that is called shared which seems like a completely different thing and it's "not used" according to DTS (arch/arm/boot/dts/bcm2835-common.dtsi):
interrupts = <1 16>,
<1 17>, <1 18>, <1 19>, <1 20>, <1 21>, <1 22>, <1 23>, <1 24>, <1 25>, <1 26>, /* dma channel 11-14 share one irq */
<1 27>, <1 27>, <1 27>, <1 27>, /* unused shared irq for all channels */ <1 28>;
> So before we could trigger IRQ #12, and now it is unbound?
Yeah, well, DMA IRQ #12 is bound to the same line as #11, but DMA IRQ #15 aka IC IRQ # INTERRUPT_DMA0+12=16+12=28 is not bound anymore indeed (the last one in the list above). Previously channels 0--12 were bound linearly and it was unclear what this hard-coded "12" is. (This 12 is never mentioned anywhere besides Qemu.) So actually 3 DMA IRQ #13-15 were unbound before.
I omitted this last DMA IRQ #15 (IC IRQ #28) — it clearly has some special status in the spec, e.g. it has a different block of DMA address, but it's not described otherwise. I assumed that "unused" means off.
Best regards, Andrey Makarov Software Team Lead Auriga LLCFrom: Philippe Mathieu-Daudé <philippe.mathieu.daude@gmail.com> on behalf of Philippe Mathieu-Daudé <f4bug@amsat.org>
Sent: Wednesday, July 13, 2022 1:45:13 AM To: Andrey Makarov; qemu-devel@nongnu.org Cc: Makarov, Andrey Subject: Re: [PATCH v2] Align Raspberry Pi DMA interrupts with Linux DTS Hi Andrey,
On 12/7/22 12:45, Andrey Makarov wrote: > There is nothing in the specs on DMA engine interrupt lines: it should have > been in the "BCM2835 ARM Peripherals" datasheet but the appropriate > "ARM peripherals interrupt table" (p.113) is nearly empty. > > All Raspberry Pi models 1-3 (based on bcm2835) have > Linux device tree (arch/arm/boot/dts/bcm2835-common.dtsi +25): > > /* dma channel 11-14 share one irq */ > > This information is repeated in the driver code > (drivers/dma/bcm2835-dma.c +1344): > > /* > * in case of channel >= 11 > * use the 11th interrupt and that is shared > */ > > In this patch channels 0--10 and 11--14 are handled separately. > > In version v2: > > 1) an OR-gate is added according to review > 2) a simple qtest is added for testing DMA & its interrupts > > Signed-off-by: Andrey Makarov <andrey.makarov@auriga.com> > --- > hw/arm/bcm2835_peripherals.c | 21 +++++- > include/hw/arm/bcm2835_peripherals.h | 2 + > tests/qtest/bcm2835-dma-test.c | 106 +++++++++++++++++++++++++++ > tests/qtest/meson.build | 3 +- > 4 files changed, 130 insertions(+), 2 deletions(-) > create mode 100644 tests/qtest/bcm2835-dma-test.c > > diff --git a/hw/arm/bcm2835_peripherals.c b/hw/arm/bcm2835_peripherals.c > index 48538c9360..5a9c472b5a 100644 > --- a/hw/arm/bcm2835_peripherals.c > +++ b/hw/arm/bcm2835_peripherals.c > @@ -101,6 +101,11 @@ static void bcm2835_peripherals_init(Object *obj) > /* DMA Channels */ > object_initialize_child(obj, "dma", &s->dma, TYPE_BCM2835_DMA); > > + object_initialize_child(obj, "dma-11-14-irq-orgate", Maybe name "shared-dma-irq-orgate"? > + &s->dma_11_14_irq_orgate, TYPE_OR_IRQ); Similarly 'shared_dma' or 'orgated-dma'? But not _11_14_. > + object_property_set_int(OBJECT(&s->dma_11_14_irq_orgate), "num-lines", 4, Instead of using a magic number: #define BCM2835_SHARED_DMA_COUNT 4 > + &error_abort); > + > object_property_add_const_link(OBJECT(&s->dma), "dma-mr", > OBJECT(&s->gpu_bus_mr)); > > @@ -322,13 +327,27 @@ static void bcm2835_peripherals_realize(DeviceState *dev, Error **errp) > memory_region_add_subregion(&s->peri_mr, DMA15_OFFSET, > sysbus_mmio_get_region(SYS_BUS_DEVICE(&s->dma), 1)); > > - for (n = 0; n <= 12; n++) { > + for (n = 0; n <= 10; n++) { So before we could trigger IRQ #12, and now it is unbound? Also: #define BCM2835_DMA_CHANNELS 10 > sysbus_connect_irq(SYS_BUS_DEVICE(&s->dma), n, > qdev_get_gpio_in_named(DEVICE(&s->ic), > BCM2835_IC_GPU_IRQ, > INTERRUPT_DMA0 + n)); > } > > + /* According to DTS, dma channels 11-14 share one irq */ > + if (!qdev_realize(DEVICE(&s->dma_11_14_irq_orgate), NULL, errp)) { > + return; > + } > + for (n = 11; n <= 14; n++) { Logic simplified if you use the [0 .. BCM2835_SHARED_DMA_COUNT-1] range: for (n = 0; n < BCM2835_SHARED_DMA_COUNT; n++) { > + sysbus_connect_irq(SYS_BUS_DEVICE(&s->dma), n, BCM2835_DMA_CHANNELS + 1 + n, > + qdev_get_gpio_in(DEVICE(&s->dma_11_14_irq_orgate), > + n - 11)); n) > + } > + qdev_connect_gpio_out(DEVICE(&s->dma_11_14_irq_orgate), 0, > + qdev_get_gpio_in_named(DEVICE(&s->ic), > + BCM2835_IC_GPU_IRQ, > + INTERRUPT_DMA0 + 11)); > + > /* THERMAL */ > if (!sysbus_realize(SYS_BUS_DEVICE(&s->thermal), errp)) { > return; > diff --git a/include/hw/arm/bcm2835_peripherals.h b/include/hw/arm/bcm2835_peripherals.h > index d864879421..79e2f2771a 100644 > --- a/include/hw/arm/bcm2835_peripherals.h > +++ b/include/hw/arm/bcm2835_peripherals.h > @@ -17,6 +17,7 @@ > #include "hw/char/bcm2835_aux.h" > #include "hw/display/bcm2835_fb.h" > #include "hw/dma/bcm2835_dma.h" > +#include "hw/or-irq.h" > #include "hw/intc/bcm2835_ic.h" > #include "hw/misc/bcm2835_property.h" > #include "hw/misc/bcm2835_rng.h" > @@ -55,6 +56,7 @@ struct BCM2835PeripheralState { > BCM2835AuxState aux; > BCM2835FBState fb; > BCM2835DMAState dma; > + qemu_or_irq dma_11_14_irq_orgate; > BCM2835ICState ic; > BCM2835PropertyState property; > BCM2835RngState rng; Regards, Phil. |
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