* [PATCH] PCI: mediatek: Fix operator precedence in PCIE_FTS_NUM_L0 macro
@ 2026-05-15 0:55 lirongqing
2026-05-15 1:27 ` Krzysztof Wilczyński
0 siblings, 1 reply; 2+ messages in thread
From: lirongqing @ 2026-05-15 0:55 UTC (permalink / raw)
To: Ryder Lee, Jianjun Wang, Lorenzo Pieralisi,
Krzysztof Wilczyński, Manivannan Sadhasivam, Rob Herring,
Bjorn Helgaas, Matthias Brugger, AngeloGioacchino Del Regno,
linux-pci, linux-mediatek, linux-arm-kernel
Cc: Li RongQing
From: Li RongQing <lirongqing@baidu.com>
The original PCIE_FTS_NUM_L0(x) macro was buggy due to improper operator
precedence, where ((x) & 0xff << 8) was evaluated as ((x) & 0xff00).
Instead of just fixing the parentheses, use the standard FIELD_PREP()
macro. This makes the code more robust by automatically handling masks
and shifts, while also adding compile-time type and range checking to
ensure the value fits within PCIE_FTS_NUM_MASK.
Fixes: 637cfacae96f ("PCI: mediatek: Add MediaTek PCIe host controller support")
Signed-off-by: Li RongQing <lirongqing@baidu.com>
---
drivers/pci/controller/pcie-mediatek.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/pci/controller/pcie-mediatek.c b/drivers/pci/controller/pcie-mediatek.c
index 7572252..00f0e29 100644
--- a/drivers/pci/controller/pcie-mediatek.c
+++ b/drivers/pci/controller/pcie-mediatek.c
@@ -61,7 +61,7 @@
/* MediaTek specific configuration registers */
#define PCIE_FTS_NUM 0x70c
#define PCIE_FTS_NUM_MASK GENMASK(15, 8)
-#define PCIE_FTS_NUM_L0(x) ((x) & 0xff << 8)
+#define PCIE_FTS_NUM_L0(x) FIELD_PREP(PCIE_FTS_NUM_MASK, x)
#define PCIE_FC_CREDIT 0x73c
#define PCIE_FC_CREDIT_MASK (GENMASK(31, 31) | GENMASK(28, 16))
--
2.9.4
^ permalink raw reply related [flat|nested] 2+ messages in thread* Re: [PATCH] PCI: mediatek: Fix operator precedence in PCIE_FTS_NUM_L0 macro
2026-05-15 0:55 [PATCH] PCI: mediatek: Fix operator precedence in PCIE_FTS_NUM_L0 macro lirongqing
@ 2026-05-15 1:27 ` Krzysztof Wilczyński
0 siblings, 0 replies; 2+ messages in thread
From: Krzysztof Wilczyński @ 2026-05-15 1:27 UTC (permalink / raw)
To: lirongqing
Cc: Ryder Lee, Jianjun Wang, Lorenzo Pieralisi, Manivannan Sadhasivam,
Rob Herring, Bjorn Helgaas, Matthias Brugger,
AngeloGioacchino Del Regno, linux-pci, linux-mediatek,
linux-arm-kernel
Hello,
> The original PCIE_FTS_NUM_L0(x) macro was buggy due to improper operator
> precedence, where ((x) & 0xff << 8) was evaluated as ((x) & 0xff00).
>
> Instead of just fixing the parentheses, use the standard FIELD_PREP()
> macro. This makes the code more robust by automatically handling masks
> and shifts, while also adding compile-time type and range checking to
> ensure the value fits within PCIE_FTS_NUM_MASK.
>
> Fixes: 637cfacae96f ("PCI: mediatek: Add MediaTek PCIe host controller support")
> Signed-off-by: Li RongQing <lirongqing@baidu.com>
> ---
> drivers/pci/controller/pcie-mediatek.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/pci/controller/pcie-mediatek.c b/drivers/pci/controller/pcie-mediatek.c
> index 7572252..00f0e29 100644
> --- a/drivers/pci/controller/pcie-mediatek.c
> +++ b/drivers/pci/controller/pcie-mediatek.c
> @@ -61,7 +61,7 @@
> /* MediaTek specific configuration registers */
> #define PCIE_FTS_NUM 0x70c
> #define PCIE_FTS_NUM_MASK GENMASK(15, 8)
> -#define PCIE_FTS_NUM_L0(x) ((x) & 0xff << 8)
> +#define PCIE_FTS_NUM_L0(x) FIELD_PREP(PCIE_FTS_NUM_MASK, x)
Aww. Nice catch! Thank you for fixing this!
Happy to offer:
Reviewed-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
All the best,
Krzysztof
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2026-05-15 0:55 [PATCH] PCI: mediatek: Fix operator precedence in PCIE_FTS_NUM_L0 macro lirongqing
2026-05-15 1:27 ` Krzysztof Wilczyński
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