linux-kernel - Re: [PATCH] [PATCH v1] spi: cadence: Add usleep_range() for cdns_spi_fill_tx

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Date:   Mon, 16 Apr 2018 12:57:11 +0100
From:   Mark Brown <broonie@...nel.org>
To:     sxauwsk <sxauwsk@....com>
Cc:     linux-spi@...r.kernel.org, linux-kernel@...r.kernel.org,
        wangshikai@...o-instrument.cn, guojian <guojian@...oinstrument.net>
Subject: Re: [PATCH] [PATCH v1] spi: cadence: Add usleep_range() for
 cdns_spi_fill_tx_fifo()

On Mon, Apr 16, 2018 at 02:46:40PM +0800, sxauwsk wrote:
> In case of xspi work in busy condition, may send bytes failed.
> once something wrong, spi controller did't work any more
> 
> My test found this situation appear in both of read/write process.
> so when TX FIFO is full, add one byte delay before send data;

This looks sensible but doesn't seem to apply against current code,
please check and resend.  

>  		/* When xspi in busy condition, bytes may send failed,
> -		 * caused communication failure so add one byte delay
> +		 * then spi control did't work thoroughly, add one byte delay
>  		 */
> -		usleep_range(10, 20);
> +		if (cdns_spi_read(xspi, CDNS_SPI_ISR_OFFSET) &
> +		    CDNS_SPI_IXR_TXFULL_MASK)
> +			usleep_range(10, 20);

It looks like this may have been sent based on a previous version of
your patch, not against the driver as it is now.

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