Re: [PATCH v4 01/13] spi: atmel-quadspi: cache MR value to avoid a write access

Boris Brezillon
2019-02-04T14:00:29Z

On Mon, 4 Feb 2019 10:09:22 +0000
<Tudor.Ambarus@microchip.com> wrote:

> From: Tudor Ambarus <tudor.ambarus@microchip.com>
>
> Set the controller by default in Serial Memory Mode (SMM) at probe.
> Cache Mode Register (MR) value to avoid write access when setting
> the controller in serial memory mode at exec_op().
>
> Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>

Reviewed-by: Boris Brezillon <bbrezillon@kernel.org>

> ---
> v4: s/smm/mr, init controller in serial memory mode by default
> v3: update smm value when different. rename mr/smm
> v2: cache MR value instead of moving the write access at probe
>
> drivers/spi/atmel-quadspi.c | 14 +++++++++++++-
> 1 file changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/spi/atmel-quadspi.c b/drivers/spi/atmel-quadspi.c
> index ddc712410812..d6864d29f294 100644
> --- a/drivers/spi/atmel-quadspi.c
> +++ b/drivers/spi/atmel-quadspi.c
> @@ -155,6 +155,7 @@ struct atmel_qspi {
> struct clk *clk;
> struct platform_device *pdev;
> u32 pending;
> + u32 mr;
> struct completion cmd_completion;
> };
>
> @@ -238,7 +239,14 @@ static int atmel_qspi_exec_op(struct spi_mem *mem, const struct spi_mem_op *op)
> icr = QSPI_ICR_INST(op->cmd.opcode);
> ifr = QSPI_IFR_INSTEN;
>
> - qspi_writel(aq, QSPI_MR, QSPI_MR_SMM);
> + /*
> + * If the QSPI controller is set in regular SPI mode, set it in
> + * Serial Memory Mode (SMM).
> + */
> + if (aq->mr != QSPI_MR_SMM) {
> + qspi_writel(aq, QSPI_MR, QSPI_MR_SMM);
> + aq->mr = QSPI_MR_SMM;
> + }
>
> mode = find_mode(op);
> if (mode < 0)
> @@ -381,6 +389,10 @@ static int atmel_qspi_init(struct atmel_qspi *aq)
> /* Reset the QSPI controller */
> qspi_writel(aq, QSPI_CR, QSPI_CR_SWRST);
>
> + /* Set the QSPI controller by default in Serial Memory Mode */
> + qspi_writel(aq, QSPI_MR, QSPI_MR_SMM);
> + aq->mr = QSPI_MR_SMM;
> +
> /* Enable the QSPI controller */
> qspi_writel(aq, QSPI_CR, QSPI_CR_QSPIEN);
>