linux-kernel - Re: [PATCH v2 1/4] spi: s3c64xx: changed to PIO mode if there is no DMA

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Date:   Wed, 19 Apr 2023 10:03:20 +0200
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Jaewon Kim <jaewon02.kim@...sung.com>,
        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 1/4] spi: s3c64xx: changed to PIO mode if there is no
 DMA

On 19/04/2023 08:06, Jaewon Kim wrote:
> Polling mode supported with qurik if there was no DMA in the SOC.

typo: quirk
You missed verb in your first part of sentence. I don't understand it.

> However, there are cased where we cannot or do not want to use DMA.
> To support this case, if DMA is not set, it is switched to polling mode.
> 
> Signed-off-by: Jaewon Kim <jaewon02.kim@...sung.com>
> ---
>  drivers/spi/spi-s3c64xx.c                 | 8 ++++++--
>  include/linux/platform_data/spi-s3c64xx.h | 1 +
>  2 files changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/spi/spi-s3c64xx.c b/drivers/spi/spi-s3c64xx.c
> index 71d324ec9a70..273aa02322d9 100644
> --- a/drivers/spi/spi-s3c64xx.c
> +++ b/drivers/spi/spi-s3c64xx.c
> @@ -19,7 +19,6 @@
>  #include <linux/platform_data/spi-s3c64xx.h>
>  
>  #define MAX_SPI_PORTS		12
> -#define S3C64XX_SPI_QUIRK_POLL		(1 << 0)
>  #define S3C64XX_SPI_QUIRK_CS_AUTO	(1 << 1)
>  #define AUTOSUSPEND_TIMEOUT	2000
>  
> @@ -116,7 +115,7 @@
>  #define S3C64XX_SPI_TRAILCNT		S3C64XX_SPI_MAX_TRAILCNT
>  
>  #define msecs_to_loops(t) (loops_per_jiffy / 1000 * HZ * t)
> -#define is_polling(x)	(x->port_conf->quirks & S3C64XX_SPI_QUIRK_POLL)
> +#define is_polling(x)	(x->cntrlr_info->polling)
>  
>  #define RXBUSY    (1<<2)
>  #define TXBUSY    (1<<3)
> @@ -1067,6 +1066,11 @@ static struct s3c64xx_spi_info *s3c64xx_spi_parse_dt(struct device *dev)
>  		sci->num_cs = temp;
>  	}
>  
> +	if (!of_find_property(dev->of_node, "dmas", NULL)) {
> +		dev_warn(dev, "cannot find DMA, changed to PIO mode\n");

You said it is desired option, so should not be a warning. I would make
it debug at most.

> +		sci->polling = 1;



Best regards,
Krzysztof