linux-kernel - Re: [PATCH 03/11] spi: Add a driver for the Freescale/NXP QuadSPI controller

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Date:   Tue, 5 Jun 2018 17:00:23 +0200
From:   Boris Brezillon <boris.brezillon@...tlin.com>
To:     Frieder Schrempf <frieder.schrempf@...eet.de>
Cc:     linux-mtd@...ts.infradead.org, linux-spi@...r.kernel.org,
        dwmw2@...radead.org, computersforpeace@...il.com,
        marek.vasut@...il.com, richard@....at, miquel.raynal@...tlin.com,
        broonie@...nel.org, david.wolfe@....com, fabio.estevam@....com,
        prabhakar.kushwaha@....com, yogeshnarayan.gaur@....com,
        han.xu@....com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 03/11] spi: Add a driver for the Freescale/NXP QuadSPI
 controller

On Wed, 30 May 2018 15:14:32 +0200
Frieder Schrempf <frieder.schrempf@...eet.de> wrote:

> +
> +static void fsl_qspi_read_ahb(struct fsl_qspi *q, const struct spi_mem_op *op)
> +{
> +	static int seq;
> +
> +	/*
> +	 * We want to avoid needing to invalidate the cache by issueing
> +	 * a reset to the AHB and Serial Flash domain, as this needs
> +	 * time. So we change the address on each read to trigger an
> +	 * actual read operation on the flash. The actual address for
> +	 * the flash memory is set by programming the LUT.
> +	 */
> +	memcpy_fromio(op->data.buf.in,
> +		      q->ahb_addr +
> +		      (seq * q->devtype_data->ahb_buf_size),
> +		      op->data.nbytes);
> +
> +	seq = seq ? 0 : 1;

We should get rid of this hack. Yogesh, Han, do you know if there's an
easy way to invalidate the AHB buffer without resetting the IP?

> +}