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Fri, 24 Apr 2026 14:05:32 -0700 (PDT) Received: from NB-6746.corp.yadro.com ([91.132.132.238]) by smtp.gmail.com with ESMTPSA id 2adb3069b0e04-5a4185ad12asm6379218e87.1.2026.04.24.14.05.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 24 Apr 2026 14:05:32 -0700 (PDT) From: Artem Shimko To: sashal@kernel.org, miquel.raynal@bootlin.com, phil.edworthy@renesas.com, =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= , Andy Shevchenko , Greg Kroah-Hartman , Jiri Slaby Cc: Artem Shimko , linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org Subject: [PATCH] serial: 8250_dw: Clean up register macros and error handling Date: Sat, 25 Apr 2026 00:05:24 +0300 Message-ID: <20260424210525.1574497-1-a.shimko.dev@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-serial@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Align register offset definitions for DW_UART_USR, DW_UART_DMASA, OCTEON_UART_USR, RZN1_UART_TDMACR and RZN1_UART_RDMACR to improve readability. Replace raw shift with FIELD_PREP() and GENMASK() for RZN1_UART_xDMACR burst field definitions — this documents that the field occupies bits [2:1] and prevents accidental overflow when new burst values are added. Simplify ENXIO handling in dw8250_probe(): instead of explicitly zeroing 'err' and then checking it, use a single conditional that allows -ENXIO (no interrupt, fall back to polling) while treating any other error as fatal. No functional change intended. Signed-off-by: Artem Shimko --- Hi, This small cleanup patch addresses a few minor style and robustness issues I noticed while working with the driver. Thank you. -- Regards, Artem drivers/tty/serial/8250/8250_dw.c | 21 ++++++++++----------- 1 file changed, 10 insertions(+), 11 deletions(-) diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c index 94beadb4024d..3e7b79154d9d 100644 --- a/drivers/tty/serial/8250/8250_dw.c +++ b/drivers/tty/serial/8250/8250_dw.c @@ -35,13 +35,13 @@ #include "8250_dwlib.h" /* Offsets for the DesignWare specific registers */ -#define DW_UART_USR 0x1f /* UART Status Register */ -#define DW_UART_DMASA 0xa8 /* DMA Software Ack */ +#define DW_UART_USR 0x1f /* UART Status Register */ +#define DW_UART_DMASA 0xa8 /* DMA Software Ack */ -#define OCTEON_UART_USR 0x27 /* UART Status Register */ +#define OCTEON_UART_USR 0x27 /* UART Status Register */ -#define RZN1_UART_TDMACR 0x10c /* DMA Control Register Transmit Mode */ -#define RZN1_UART_RDMACR 0x110 /* DMA Control Register Receive Mode */ +#define RZN1_UART_TDMACR 0x10c /* DMA Control Register Transmit Mode */ +#define RZN1_UART_RDMACR 0x110 /* DMA Control Register Receive Mode */ /* DesignWare specific register fields */ #define DW_UART_IIR_IID GENMASK(3, 0) @@ -52,9 +52,10 @@ /* Renesas specific register fields */ #define RZN1_UART_xDMACR_DMA_EN BIT(0) -#define RZN1_UART_xDMACR_1_WORD_BURST (0 << 1) -#define RZN1_UART_xDMACR_4_WORD_BURST (1 << 1) -#define RZN1_UART_xDMACR_8_WORD_BURST (2 << 1) +#define RZN1_UART_xDMACR_BURST_MASK GENMASK(2, 1) +#define RZN1_UART_xDMACR_1_WORD_BURST FIELD_PREP(RZN1_UART_xDMACR_BURST_MASK, 0) +#define RZN1_UART_xDMACR_4_WORD_BURST FIELD_PREP(RZN1_UART_xDMACR_BURST_MASK, 1) +#define RZN1_UART_xDMACR_8_WORD_BURST FIELD_PREP(RZN1_UART_xDMACR_BURST_MASK, 2) #define RZN1_UART_xDMACR_BLK_SZ(x) ((x) << 3) /* Quirks */ @@ -729,9 +730,7 @@ static int dw8250_probe(struct platform_device *pdev) err = uart_read_port_properties(p); /* no interrupt -> fall back to polling */ - if (err == -ENXIO) - err = 0; - if (err) + if (err && err != -ENXIO) return err; switch (p->iotype) { -- 2.43.0