Re: [cip-dev] [PATCH v3 4.19.y-cip 13/17] spi: spi-mem: Add a new API to support direct mapping

["Pavel Machek" <pavel@denx.de>]

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Hi!

> From: Boris Brezillon <boris.brezillon@bootlin.com>
> 
> commit aa167f3fed0c37e0e4c707d4331d827661f46644 upstream.
> 
> Most modern SPI controllers can directly map a SPI memory (or a portion
> of the SPI memory) in the CPU address space. Most of the time this
> brings significant performance improvements as it automates the whole
> process of sending SPI memory operations every time a new region is
> accessed.
> 
> This new API allows SPI memory drivers to create direct mappings and
> then use them to access the memory instead of using spi_mem_exec_op().

This can be refactored to remove if/else nesting.

> +ssize_t spi_mem_dirmap_read(struct spi_mem_dirmap_desc *desc,
> +			    u64 offs, size_t len, void *buf)
> +{
> +	struct spi_controller *ctlr = desc->mem->spi->controller;
> +	ssize_t ret;
> +
> +	if (desc->info.op_tmpl.data.dir != SPI_MEM_DATA_IN)
> +		return -EINVAL;
> +
> +	if (!len)
> +		return 0;
> +
> +	if (desc->nodirmap) {
> +		ret = spi_mem_no_dirmap_read(desc, offs, len, buf);
> +	} else if (ctlr->mem_ops && ctlr->mem_ops->dirmap_read) {
> +		ret = spi_mem_access_start(desc->mem);
> +		if (ret)
> +			return ret;
> +
> +		ret = ctlr->mem_ops->dirmap_read(desc, offs, len, buf);
> +
> +		spi_mem_access_end(desc->mem);
> +	} else {
> +		ret = -ENOTSUPP;
> +	}
> +
> +	return ret;
> +}

This can be

     if (desc->nodirmap)
     	return spi_mem_no_dirmap_read(desc, offs, len, buf);
     if (!(ctlr->mem_ops && ctlr->mem_ops->dirmap_read))
     	return -ENOTSUPP;

     ... normal case goes here...

Same refactoring can be done for dirmap_write.

Code works either way and is not too bad, so... up to you :-).

Best regards,
								Pavel
-- 
DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany

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