From mboxrd@z Thu Jan 1 00:00:00 1970 From: Boris Brezillon Subject: Re: [PATCH 1/9] spi: atmel-quadspi: optimize qspi init Date: Wed, 30 Jan 2019 18:15:15 +0100 Message-ID: <20190130181505.4f495d3a@bbrezillon> References: <20190130150818.24902-1-tudor.ambarus@microchip.com> <20190130150818.24902-2-tudor.ambarus@microchip.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: , , , , linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-spi@vger.kernel.org To: Return-path: In-Reply-To: <20190130150818.24902-2-tudor.ambarus@microchip.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-spi.vger.kernel.org On Wed, 30 Jan 2019 15:08:29 +0000 wrote: > From: Tudor Ambarus > > Set the QSPI controller in Serial Memory Mode at init and not > at each exec_op() call. If you ever want to support regular SPI you'll have to put it back to atmel_qspi_exec_op(), so I'm not sure this is a good move. Another approach would be to cache the MR value to avoid doing a write access on the bus when the value hasn't changed. > > Signed-off-by: Tudor Ambarus > --- > drivers/spi/atmel-quadspi.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/drivers/spi/atmel-quadspi.c b/drivers/spi/atmel-quadspi.c > index ddc712410812..f79b17792a11 100644 > --- a/drivers/spi/atmel-quadspi.c > +++ b/drivers/spi/atmel-quadspi.c > @@ -238,8 +238,6 @@ 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); > - > mode = find_mode(op); > if (mode < 0) > return -ENOTSUPP; > @@ -381,6 +379,9 @@ 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 in Serial Memory Mode */ > + qspi_writel(aq, QSPI_MR, QSPI_MR_SMM); > + > /* Enable the QSPI controller */ > qspi_writel(aq, QSPI_CR, QSPI_CR_QSPIEN); >