[PATCH] irqchip/gic-v3: Fix GIC_LINE_NR accessor

[PATCH] irqchip/gic-v3: Fix GIC_LINE_NR accessor

[Zenghui Yu]

As per GIC spec, ITLinesNumber indicates the maximum SPI INTID that
the GIC implementation supports. And the maximum SPI INTID an
implementation might support is 1019 (field value 11111).

max(GICD_TYPER_SPIS(...), 1020) is not what we actually want for
GIC_LINE_NR. Fix it to min(GICD_TYPER_SPIS(...), 1020).

Signed-off-by: Zenghui Yu <yuzenghui@huawei.com>
---

Hi Marc,

I still see "GICv3: 992 SPIs implemented" on the host. I go back to
https://patchwork.kernel.org/patch/11078623/ and it seems that we
failed to make the GIC_LINE_NR correct at that time.

 drivers/irqchip/irq-gic-v3.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
index 7b0c96b9e02f..f4a49aef5ca4 100644
--- a/drivers/irqchip/irq-gic-v3.c
+++ b/drivers/irqchip/irq-gic-v3.c
@@ -59,7 +59,7 @@ static struct gic_chip_data gic_data __read_mostly;
 static DEFINE_STATIC_KEY_TRUE(supports_deactivate_key);
 
 #define GIC_ID_NR	(1U << GICD_TYPER_ID_BITS(gic_data.rdists.gicd_typer))
-#define GIC_LINE_NR	max(GICD_TYPER_SPIS(gic_data.rdists.gicd_typer), 1020U)
+#define GIC_LINE_NR	min(GICD_TYPER_SPIS(gic_data.rdists.gicd_typer), 1020U)
 #define GIC_ESPI_NR	GICD_TYPER_ESPIS(gic_data.rdists.gicd_typer)
 
 /*
-- 
2.19.1



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Re: [PATCH] irqchip/gic-v3: Fix GIC_LINE_NR accessor

[Marc Zyngier]

On 18/09/2019 07:57, Zenghui Yu wrote:
> As per GIC spec, ITLinesNumber indicates the maximum SPI INTID that
> the GIC implementation supports. And the maximum SPI INTID an
> implementation might support is 1019 (field value 11111).
> 
> max(GICD_TYPER_SPIS(...), 1020) is not what we actually want for
> GIC_LINE_NR. Fix it to min(GICD_TYPER_SPIS(...), 1020).
> 
> Signed-off-by: Zenghui Yu <yuzenghui@huawei.com>
> ---
> 
> Hi Marc,
> 
> I still see "GICv3: 992 SPIs implemented" on the host. I go back to
> https://patchwork.kernel.org/patch/11078623/ and it seems that we
> failed to make the GIC_LINE_NR correct at that time.

Ah, nice catch. Clearly, I didn't have my head screwed on properly when
I wrote this. I'll take this in for the next round of fixes.

Thanks,

	M.
-- 
Jazz is not dead, it just smells funny...

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