Re: [PATCH 02/33] powerpc/legacy_serial: cache serial port and info in add_legacy_port()

Ilpo Järvinen
2025-06-11T11:16:11Z

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On Wed, 11 Jun 2025, Jiri Slaby (SUSE) wrote:

> Caching the port and info in local variables makes the code more compact
> and easier to understand.
>
> Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
> Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: Nicholas Piggin <npiggin@gmail.com>
> Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
> Cc: linuxppc-dev@lists.ozlabs.org

Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

--
i.

> ---
> arch/powerpc/kernel/legacy_serial.c | 52 ++++++++++++++---------------
> 1 file changed, 26 insertions(+), 26 deletions(-)
>
> diff --git a/arch/powerpc/kernel/legacy_serial.c b/arch/powerpc/kernel/legacy_serial.c
> index 1da2f6e7d2a1..d9080189c28c 100644
> --- a/arch/powerpc/kernel/legacy_serial.c
> +++ b/arch/powerpc/kernel/legacy_serial.c
> @@ -77,6 +77,8 @@ static int __init add_legacy_port(struct device_node *np, int want_index,
> phys_addr_t taddr, unsigned long irq,
> upf_t flags, int irq_check_parent)
> {
> + struct plat_serial8250_port *legacy_port;
> + struct legacy_serial_info *legacy_info;
> const __be32 *clk, *spd, *rs;
> u32 clock = BASE_BAUD * 16;
> u32 shift = 0;
> @@ -110,16 +112,17 @@ static int __init add_legacy_port(struct device_node *np, int want_index,
> if (index >= legacy_serial_count)
> legacy_serial_count = index + 1;
>
> + legacy_port = &legacy_serial_ports[index];
> + legacy_info = &legacy_serial_infos[index];
> +
> /* Check if there is a port who already claimed our slot */
> - if (legacy_serial_infos[index].np != NULL) {
> + if (legacy_info->np != NULL) {
> /* if we still have some room, move it, else override */
> if (legacy_serial_count < MAX_LEGACY_SERIAL_PORTS) {
> printk(KERN_DEBUG "Moved legacy port %d -> %d\n",
> index, legacy_serial_count);
> - legacy_serial_ports[legacy_serial_count] =
> - legacy_serial_ports[index];
> - legacy_serial_infos[legacy_serial_count] =
> - legacy_serial_infos[index];
> + legacy_serial_ports[legacy_serial_count] = *legacy_port;
> + legacy_serial_infos[legacy_serial_count] = *legacy_info;
> legacy_serial_count++;
> } else {
> printk(KERN_DEBUG "Replacing legacy port %d\n", index);
> @@ -127,36 +130,33 @@ static int __init add_legacy_port(struct device_node *np, int want_index,
> }
>
> /* Now fill the entry */
> - memset(&legacy_serial_ports[index], 0,
> - sizeof(struct plat_serial8250_port));
> + memset(legacy_port, 0, sizeof(*legacy_port));
> if (iotype == UPIO_PORT)
> - legacy_serial_ports[index].iobase = base;
> + legacy_port->iobase = base;
> else
> - legacy_serial_ports[index].mapbase = base;
> -
> - legacy_serial_ports[index].iotype = iotype;
> - legacy_serial_ports[index].uartclk = clock;
> - legacy_serial_ports[index].irq = irq;
> - legacy_serial_ports[index].flags = flags;
> - legacy_serial_ports[index].regshift = shift;
> - legacy_serial_infos[index].taddr = taddr;
> - legacy_serial_infos[index].np = of_node_get(np);
> - legacy_serial_infos[index].clock = clock;
> - legacy_serial_infos[index].speed = spd ? be32_to_cpup(spd) : 0;
> - legacy_serial_infos[index].irq_check_parent = irq_check_parent;
> + legacy_port->mapbase = base;
> +
> + legacy_port->iotype = iotype;
> + legacy_port->uartclk = clock;
> + legacy_port->irq = irq;
> + legacy_port->flags = flags;
> + legacy_port->regshift = shift;
> + legacy_info->taddr = taddr;
> + legacy_info->np = of_node_get(np);
> + legacy_info->clock = clock;
> + legacy_info->speed = spd ? be32_to_cpup(spd) : 0;
> + legacy_info->irq_check_parent = irq_check_parent;
>
> if (iotype == UPIO_TSI) {
> - legacy_serial_ports[index].serial_in = tsi_serial_in;
> - legacy_serial_ports[index].serial_out = tsi_serial_out;
> + legacy_port->serial_in = tsi_serial_in;
> + legacy_port->serial_out = tsi_serial_out;
> }
>
> - printk(KERN_DEBUG "Found legacy serial port %d for %pOF\n",
> - index, np);
> + printk(KERN_DEBUG "Found legacy serial port %d for %pOF\n", index, np);
> printk(KERN_DEBUG " %s=%llx, taddr=%llx, irq=%lx, clk=%d, speed=%d\n",
> (iotype == UPIO_PORT) ? "port" : "mem",
> (unsigned long long)base, (unsigned long long)taddr, irq,
> - legacy_serial_ports[index].uartclk,
> - legacy_serial_infos[index].speed);
> + legacy_port->uartclk, legacy_info->speed);
>
> return index;
> }
>