linux-kernel - Re: [PATCH v2 4/4] spi: s3c64xx: support interrupt based pio mode

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Date:   Wed, 19 Apr 2023 18:45:08 +0900
From:   Jaewon Kim <jaewon02.kim@...sung.com>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        Mark Brown <broonie@...nel.org>, Andi Shyti <andi@...zian.org>,
        Alim Akhtar <alim.akhtar@...sung.com>
Cc:     linux-spi@...r.kernel.org, linux-samsung-soc@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Chanho Park <chanho61.park@...sung.com>
Subject: Re: [PATCH v2 4/4] spi: s3c64xx: support interrupt based pio mode


On 23. 4. 19. 17:21, Krzysztof Kozlowski wrote:
> On 19/04/2023 08:06, Jaewon Kim wrote:
>> Interrupt based pio mode is supported to reduce CPU load.
>> If transfer size is larger than 32 byte, it is processed using interrupt.
>>
>> Signed-off-by: Jaewon Kim <jaewon02.kim@...sung.com>
>> ---
>>   drivers/spi/spi-s3c64xx.c | 82 ++++++++++++++++++++++++++++++++-------
>>   1 file changed, 67 insertions(+), 15 deletions(-)
>>
>> diff --git a/drivers/spi/spi-s3c64xx.c b/drivers/spi/spi-s3c64xx.c
>> index cf3060b2639b..ce1afb9a4ed4 100644
>> --- a/drivers/spi/spi-s3c64xx.c
>> +++ b/drivers/spi/spi-s3c64xx.c
>> @@ -58,6 +58,8 @@
>>   #define S3C64XX_SPI_MODE_BUS_TSZ_HALFWORD	(1<<17)
>>   #define S3C64XX_SPI_MODE_BUS_TSZ_WORD		(2<<17)
>>   #define S3C64XX_SPI_MODE_BUS_TSZ_MASK		(3<<17)
>> +#define S3C64XX_SPI_MODE_RX_RDY_LVL		GENMASK(16, 11)
>> +#define S3C64XX_SPI_MODE_RX_RDY_LVL_SHIFT	11
>>   #define S3C64XX_SPI_MODE_SELF_LOOPBACK		(1<<3)
>>   #define S3C64XX_SPI_MODE_RXDMA_ON		(1<<2)
>>   #define S3C64XX_SPI_MODE_TXDMA_ON		(1<<1)
>> @@ -114,6 +116,8 @@
>>   
>>   #define S3C64XX_SPI_TRAILCNT		S3C64XX_SPI_MAX_TRAILCNT
>>   
>> +#define S3C64XX_SPI_POLLING_SIZE	32
>> +
>>   #define msecs_to_loops(t) (loops_per_jiffy / 1000 * HZ * t)
>>   #define is_polling(x)	(x->cntrlr_info->polling)
>>   
>> @@ -552,10 +556,11 @@ static int s3c64xx_wait_for_dma(struct s3c64xx_spi_driver_data *sdd,
>>   }
>>   
>>   static int s3c64xx_wait_for_pio(struct s3c64xx_spi_driver_data *sdd,
>> -				struct spi_transfer *xfer)
>> +				struct spi_transfer *xfer, int use_irq)
>>   {
>>   	void __iomem *regs = sdd->regs;
>>   	unsigned long val;
>> +	unsigned long time;
>>   	u32 status;
>>   	int loops;
>>   	u32 cpy_len;
>> @@ -563,17 +568,24 @@ static int s3c64xx_wait_for_pio(struct s3c64xx_spi_driver_data *sdd,
>>   	int ms;
>>   	u32 tx_time;
>>   
>> -	/* sleep during signal transfer time */
>> -	status = readl(regs + S3C64XX_SPI_STATUS);
>> -	if (RX_FIFO_LVL(status, sdd) < xfer->len) {
>> -		tx_time = (xfer->len * 8 * 1000 * 1000) / sdd->cur_speed;
>> -		usleep_range(tx_time / 2, tx_time);
>> -	}
> You just added this code. Adding and immediately removing it, suggests
> this should be one patch.
>
This code has been moved, not removed.


+       if (use_irq) {
+               val = msecs_to_jiffies(ms);
+               time = 
wait_for_completion_timeout(&sdd->xfer_completion, val);
+               if (!time)
+                       return -EIO;
+       } else {
+               /* sleep during signal transfer time */
+               status = readl(regs + S3C64XX_SPI_STATUS);
+               if (RX_FIFO_LVL(status, sdd) < xfer->len) {
+                       tx_time = (xfer->len * 8 * 1000 * 1000) / 
sdd->cur_speed;
+                       usleep_range(tx_time / 2, tx_time);
+               }
+       }
+


> Best regards,
> Krzysztof
>
>

Thanks

Jaewon Kim