linux-kernel - [PATCH 18/18] tty: serial: samsung: shrink memory footprint of ``struct s3c24xx_uart

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Message-ID: <20240110102102.61587-19-tudor.ambarus@linaro.org>
Date: Wed, 10 Jan 2024 10:21:02 +0000
From: Tudor Ambarus <tudor.ambarus@...aro.org>
To: krzysztof.kozlowski@...aro.org,
	alim.akhtar@...sung.com,
	gregkh@...uxfoundation.org,
	jirislaby@...nel.org
Cc: linux-arm-kernel@...ts.infradead.org,
	linux-samsung-soc@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-serial@...r.kernel.org,
	andre.draszik@...aro.org,
	peter.griffin@...aro.org,
	kernel-team@...roid.com,
	willmcvicker@...gle.com,
	Tudor Ambarus <tudor.ambarus@...aro.org>
Subject: [PATCH 18/18] tty: serial: samsung: shrink memory footprint of ``struct s3c24xx_uart_info``

Use u32 for the members of ``struct s3c24xx_uart_info`` that are used
for register interactions. The purpose of these members becomes clearer.

The greater benefit of this change is that it also reduces the memory
footprint of the struct, allowing 64-bit architectures to use a
single cacheline for the entire struct.

struct s3c24xx_uart_info {
	const char  *              name;                 /*     0     8 */
	enum s3c24xx_port_type     type;                 /*     8     4 */
	unsigned int               port_type;            /*    12     4 */
	unsigned int               fifosize;             /*    16     4 */
	u32                        rx_fifomask;          /*    20     4 */
	u32                        rx_fifoshift;         /*    24     4 */
	u32                        rx_fifofull;          /*    28     4 */
	u32                        tx_fifomask;          /*    32     4 */
	u32                        tx_fifoshift;         /*    36     4 */
	u32                        tx_fifofull;          /*    40     4 */
	u32                        clksel_mask;          /*    44     4 */
	u32                        clksel_shift;         /*    48     4 */
	u32                        ucon_mask;            /*    52     4 */
	u8                         def_clk_sel;          /*    56     1 */
	u8                         num_clks;             /*    57     1 */
	u8                         iotype;               /*    58     1 */
	u8                         has_divslot:1;        /*    59: 0  1 */

	/* size: 64, cachelines: 1, members: 17 */
	/* padding: 4 */
	/* bit_padding: 7 bits */
};

Signed-off-by: Tudor Ambarus <tudor.ambarus@...aro.org>
---
 drivers/tty/serial/samsung_tty.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/drivers/tty/serial/samsung_tty.c b/drivers/tty/serial/samsung_tty.c
index 598d9fe7a492..40dceb41acb7 100644
--- a/drivers/tty/serial/samsung_tty.c
+++ b/drivers/tty/serial/samsung_tty.c
@@ -75,15 +75,15 @@ struct s3c24xx_uart_info {
 	enum s3c24xx_port_type	type;
 	unsigned int		port_type;
 	unsigned int		fifosize;
-	unsigned long		rx_fifomask;
-	unsigned long		rx_fifoshift;
-	unsigned long		rx_fifofull;
-	unsigned long		tx_fifomask;
-	unsigned long		tx_fifoshift;
-	unsigned long		tx_fifofull;
-	unsigned long		clksel_mask;
-	unsigned long		clksel_shift;
-	unsigned long		ucon_mask;
+	u32			rx_fifomask;
+	u32			rx_fifoshift;
+	u32			rx_fifofull;
+	u32			tx_fifomask;
+	u32			tx_fifoshift;
+	u32			tx_fifofull;
+	u32			clksel_mask;
+	u32			clksel_shift;
+	u32			ucon_mask;
 	u8			def_clk_sel;
 	u8			num_clks;
 	u8			iotype;
-- 
2.43.0.472.g3155946c3a-goog