linux-kernel - Re: [PATCH v5 1/2] spi: dw: Add 32 bpw support to DW DMA Controller

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Message-ID: <ZDVO/fpOZm+lGVZE@smile.fi.intel.com>
Date:   Tue, 11 Apr 2023 15:13:49 +0300
From:   Andy Shevchenko <andriy.shevchenko@...el.com>
To:     Joy Chakraborty <joychakr@...gle.com>
Cc:     Serge Semin <fancer.lancer@...il.com>,
        Mark Brown <broonie@...nel.org>, linux-spi@...r.kernel.org,
        linux-kernel@...r.kernel.org, manugautam@...gle.com,
        rohitner@...gle.com
Subject: Re: [PATCH v5 1/2] spi: dw: Add 32 bpw support to DW DMA Controller

On Thu, Mar 30, 2023 at 06:34:49AM +0000, Joy Chakraborty wrote:

First of all the Subject is wrong. You are not touching DMA controller.
Needs to be rephrased.

> Add Support for AxSize = 4 bytes configuration from dw dma driver if

SPI DMA driver

(or something like this, note capital letters for acronyms).

> n_bytes i.e. number of bytes per write to fifo is 3 or 4.
> 
> Number of bytes written to fifo per write is depended on the bits/word
> configuration being used which the DW core driver translates to n_bytes.

...

>  static enum dma_slave_buswidth dw_spi_dma_convert_width(u8 n_bytes)
>  {
> -	if (n_bytes == 1)
> +	switch (n_bytes) {
> +	case 1:
>  		return DMA_SLAVE_BUSWIDTH_1_BYTE;
> -	else if (n_bytes == 2)
> +	case 2:
>  		return DMA_SLAVE_BUSWIDTH_2_BYTES;
> -
> -	return DMA_SLAVE_BUSWIDTH_UNDEFINED;

> +	case 3:

I'm not sure about this.

> +	case 4:
> +		return DMA_SLAVE_BUSWIDTH_4_BYTES;
> +	default:
> +		return DMA_SLAVE_BUSWIDTH_UNDEFINED;
> +	}
>  }

-- 
With Best Regards,
Andy Shevchenko