linux-kernel - Re: [PATCH 1/3] mtd: spi-nor: Use the spi-mem poll status APIs.

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Date:   Sat, 23 Jul 2022 11:30:16 +0300
From:   Sergey Shtylyov <s.shtylyov@....ru>
To:     周琰杰 (Zhou Yanjie) 
        <zhouyanjie@...yeetech.com>, <tudor.ambarus@...rochip.com>,
        <p.yadav@...com>, <michael@...le.cc>, <miquel.raynal@...tlin.com>,
        <richard@....at>, <vigneshr@...com>, <broonie@...nel.org>,
        <robh+dt@...nel.org>, <krzysztof.kozlowski+dt@...aro.org>
CC:     <linux-mtd@...ts.infradead.org>, <linux-spi@...r.kernel.org>,
        <linux-mips@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <aidanmacdonald.0x0@...il.com>,
        <tmn505@...il.com>, <paul@...pouillou.net>,
        <dongsheng.qiu@...enic.com>, <aric.pzqi@...enic.com>,
        <rick.tyliu@...enic.com>, <jinghui.liu@...enic.com>,
        <sernia.zhou@...mail.com>, <reimu@...omaker.com>
Subject: Re: [PATCH 1/3] mtd: spi-nor: Use the spi-mem poll status APIs.

Hello!

On 7/22/22 7:48 PM, 周琰杰 (Zhou Yanjie) wrote:

> With advanced controllers (such as Ingenic SFC), it is possible to poll
> the status register of the device. This could be done to offload the CPU
> during a erase or write operation. Make use of spi-mem poll status APIs
> to handle this feature.
> 
> Previously, when erasing large area (e.g. 32MiB), in non-offload case,
> CPU load could reach ~90% and would generate ~3.92 million interrupts,
> now it decrease to ~15% CPU load and 0.15 million interrupts.
> 
> This should also fix the high CPU usage for system which don't have a
> dedicated poll status block logic (decrease to ~80% CPU load and ~1.61
> million interrupts.).
> 
> Signed-off-by: 周琰杰 (Zhou Yanjie) <zhouyanjie@...yeetech.com>
> ---
>  drivers/mtd/spi-nor/core.c | 42 ++++++++++++++++++++++++++++++++----------
>  1 file changed, 32 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
> index 502967c..6a31132 100644
> --- a/drivers/mtd/spi-nor/core.c
> +++ b/drivers/mtd/spi-nor/core.c
> @@ -617,19 +617,41 @@ static int spi_nor_wait_till_ready_with_timeout(struct spi_nor *nor,
>  	unsigned long deadline;
>  	int timeout = 0, ret;
>  
> -	deadline = jiffies + timeout_jiffies;
> +	if (nor->spimem && !nor->params->ready) {
> +		struct spi_mem_op op = SPI_MEM_OP(SPI_MEM_OP_CMD(SPINOR_OP_RDSR, 0),
> +						       SPI_MEM_OP_NO_ADDR,
> +						       SPI_MEM_OP_NO_DUMMY,
> +						       SPI_MEM_OP_DATA_IN(1, nor->bouncebuf, 0));

   Strange indentation...

[...]
> +		return spi_mem_poll_status(nor->spimem, &op, SR_WIP, 0, 0, 10,
> +						       jiffies_to_msecs(timeout_jiffies));

   Here as well...

[...]

MBR, Sergey