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Date: Fri, 19 Jan 2024 08:36:21 +0300
From: Dan Carpenter <dan.carpenter@linaro.org>
To: dregan@broadcom.com
Cc: dregan@mail.com, miquel.raynal@bootlin.com, richard@nod.at,
	vigneshr@ti.com, robh+dt@kernel.org,
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Subject: Re: [PATCH v2 05/10] mtd: rawnand: brcmnand: Add BCMBCA read data
 bus interface
Message-ID: <4b3f4316-0da4-4fde-a806-7b579948db50@moroto.mountain>
References: <20240118195356.133391-1-dregan@broadcom.com>
 <20240118195356.133391-6-dregan@broadcom.com>
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In-Reply-To: <20240118195356.133391-6-dregan@broadcom.com>

On Thu, Jan 18, 2024 at 11:53:51AM -0800, dregan@broadcom.com wrote:
> diff --git a/drivers/mtd/nand/raw/brcmnand/bcmbca_nand.c b/drivers/mtd/nand/raw/brcmnand/bcmbca_nand.c
> index 3e2f3b79788d..e97e13ae246c 100644
> --- a/drivers/mtd/nand/raw/brcmnand/bcmbca_nand.c
> +++ b/drivers/mtd/nand/raw/brcmnand/bcmbca_nand.c
> @@ -26,6 +26,18 @@ enum {
>  	BCMBCA_CTLRDY		= BIT(4),
>  };
>  
> +#if defined(CONFIG_ARM64)
> +#define ALIGN_REQ		8
> +#else
> +#define ALIGN_REQ		4
> +#endif
> +
> +static inline bool bcmbca_nand_is_buf_aligned(void *flash_cache,  void *buffer)
> +{
> +	return IS_ALIGNED((uintptr_t)buffer, ALIGN_REQ) &&
> +				IS_ALIGNED((uintptr_t)flash_cache, ALIGN_REQ);
> +}
> +
>  static bool bcmbca_nand_intc_ack(struct brcmnand_soc *soc)
>  {
>  	struct bcmbca_nand_soc *priv =
> @@ -56,6 +68,20 @@ static void bcmbca_nand_intc_set(struct brcmnand_soc *soc, bool en)
>  	brcmnand_writel(val, mmio);
>  }
>  
> +static void bcmbca_read_data_bus(struct brcmnand_soc *soc,
> +				 void __iomem *flash_cache,  u32 *buffer, int fc_words)
> +{
> +	/*
> +	 * memcpy can do unaligned aligned access depending on source
> +	 * and dest address, which is incompatible with nand cache. Fallback
> +	 * to the memcpy for io version
> +	 */
> +	if (bcmbca_nand_is_buf_aligned((void *)flash_cache, buffer))
> +		memcpy((void *)buffer, (void *)flash_cache, fc_words * 4);
> +	else
> +		memcpy_fromio((void *)buffer, flash_cache, fc_words * 4);
> +}

This comment is confusing or maybe the if statement is reversed...
We're falling back to memcpy_fromio() for the unaligned accesses but the
comment says we're falling back to memcpy().

regards,
dan carpenter