linux-kernel - Re: [PATCH v2 1/2] dmaengine: at_hdmac: Repair bitfield macros for peripheral ID handling

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Date:   Tue, 23 May 2023 18:24:53 +0100
From:   Tudor Ambarus <tudor.ambarus@...aro.org>
To:     Peter Rosin <peda@...ntia.se>, LKML <linux-kernel@...r.kernel.org>
Cc:     Ludovic Desroches <ludovic.desroches@...rochip.com>,
        Vinod Koul <vkoul@...nel.org>,
        Nicolas Ferre <nicolas.ferre@...rochip.com>,
        linux-arm-kernel@...ts.infradead.org, dmaengine@...r.kernel.org,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
Subject: Re: [PATCH v2 1/2] dmaengine: at_hdmac: Repair bitfield macros for
 peripheral ID handling



On 5/23/23 18:20, Peter Rosin wrote:
> The MSB part of the peripheral IDs need to go into the ATC_SRC_PER_MSB
> and ATC_DST_PER_MSB fields. Not the LSB part.
> 
> This fixes a severe regression for TSE-850 devices (compatible
> axentia,tse850v3) where output to the audio I2S codec (the main
> purpose of the device) simply do not work.
> 
> Fixes: d8840a7edcf0 ("dmaengine: at_hdmac: Use bitfield access macros")
> Cc: stable@...r.kernel.org
> Signed-off-by: Peter Rosin <peda@...ntia.se>

Reviewed-by: Tudor Ambarus <tudor.ambarus@...aro.org>

> ---
>  drivers/dma/at_hdmac.c | 15 +++++++++------
>  1 file changed, 9 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c
> index 8858470246e1..6362013b90df 100644
> --- a/drivers/dma/at_hdmac.c
> +++ b/drivers/dma/at_hdmac.c
> @@ -153,8 +153,6 @@
>  #define ATC_AUTO		BIT(31)		/* Auto multiple buffer tx enable */
>  
>  /* Bitfields in CFG */
> -#define ATC_PER_MSB(h)	((0x30U & (h)) >> 4)	/* Extract most significant bits of a handshaking identifier */
> -
>  #define ATC_SRC_PER		GENMASK(3, 0)	/* Channel src rq associated with periph handshaking ifc h */
>  #define ATC_DST_PER		GENMASK(7, 4)	/* Channel dst rq associated with periph handshaking ifc h */
>  #define ATC_SRC_REP		BIT(8)		/* Source Replay Mod */
> @@ -181,10 +179,15 @@
>  #define ATC_DPIP_HOLE		GENMASK(15, 0)
>  #define ATC_DPIP_BOUNDARY	GENMASK(25, 16)
>  
> -#define ATC_SRC_PER_ID(id)	(FIELD_PREP(ATC_SRC_PER_MSB, (id)) |	\
> -				 FIELD_PREP(ATC_SRC_PER, (id)))
> -#define ATC_DST_PER_ID(id)	(FIELD_PREP(ATC_DST_PER_MSB, (id)) |	\
> -				 FIELD_PREP(ATC_DST_PER, (id)))
> +#define ATC_PER_MSB		GENMASK(5, 4)	/* Extract MSBs of a handshaking identifier */
> +#define ATC_SRC_PER_ID(id)					       \
> +	({ typeof(id) _id = (id);				       \
> +	   FIELD_PREP(ATC_SRC_PER_MSB, FIELD_GET(ATC_PER_MSB, _id)) |  \
> +	   FIELD_PREP(ATC_SRC_PER, _id); })
> +#define ATC_DST_PER_ID(id)					       \
> +	({ typeof(id) _id = (id);				       \
> +	   FIELD_PREP(ATC_DST_PER_MSB, FIELD_GET(ATC_PER_MSB, _id)) |  \
> +	   FIELD_PREP(ATC_DST_PER, _id); })
>  
>  
>