From: Pratyush Yadav <p.yadav@ti.com>
To: Yoshitaka Ikeda <ikeda@nskint.co.jp>
Cc: Mark Brown <broonie@kernel.org>,
Philipp Zabel <p.zabel@pengutronix.de>,
"linux-spi@vger.kernel.org" <linux-spi@vger.kernel.org>,
Masahiro Mizutani <m.mizutani@nskint.co.jp>,
Ken Kurematsu <k.kurematsu@nskint.co.jp>
Subject: Re: [PATCH] spi: Fixed division by zero warning
Date: Fri, 17 Sep 2021 22:12:01 +0530 [thread overview]
Message-ID: <20210917164159.n75ccthyvfrud2i7@ti.com> (raw)
In-Reply-To: <OSZPR01MB70049C8F56ED8902852DF97B8BD49@OSZPR01MB7004.jpnprd01.prod.outlook.com>
Hi Yoshitaka,
On 08/09/21 05:29AM, Yoshitaka Ikeda wrote:
> The reason for dividing by zero is because the dummy bus width is zero,
> but if the dummy n bytes is zero, it indicates that there is no data transfer,
> so there is no need for calculation.
>
> Fixes: 7512eaf54190 ("spi: cadence-quadspi: Fix dummy cycle calculation when buswidth > 1")
You are right, there is no need for this.
> Signed-off-by: Yoshitaka Ikeda <ikeda@nskint.co.jp>
> ---
> drivers/spi/atmel-quadspi.c | 2 +-
> drivers/spi/spi-bcm-qspi.c | 3 ++-
> drivers/spi/spi-mtk-nor.c | 2 +-
> drivers/spi/spi-stm32-qspi.c | 2 +-
> 4 files changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/spi/atmel-quadspi.c b/drivers/spi/atmel-quadspi.c
> index 95d4fa32c299..92d9610df1fd 100644
> --- a/drivers/spi/atmel-quadspi.c
> +++ b/drivers/spi/atmel-quadspi.c
> @@ -310,7 +310,7 @@ static int atmel_qspi_set_cfg(struct atmel_qspi *aq,
> return mode;
> ifr |= atmel_qspi_modes[mode].config;
>
> - if (op->dummy.buswidth && op->dummy.nbytes)
> + if (op->dummy.nbytes)
> dummy_cycles = op->dummy.nbytes * 8 / op->dummy.buswidth;
>
> /*
> diff --git a/drivers/spi/spi-bcm-qspi.c b/drivers/spi/spi-bcm-qspi.c
> index a78e56f566dd..0d95fe54b3c0 100644
> --- a/drivers/spi/spi-bcm-qspi.c
> +++ b/drivers/spi/spi-bcm-qspi.c
> @@ -395,7 +395,8 @@ static int bcm_qspi_bspi_set_flex_mode(struct bcm_qspi *qspi,
> if (addrlen == BSPI_ADDRLEN_4BYTES)
> bpp = BSPI_BPP_ADDR_SELECT_MASK;
>
> - bpp |= (op->dummy.nbytes * 8) / op->dummy.buswidth;
> + if (op->dummy.nbytes)
> + bpp |= (op->dummy.nbytes * 8) / op->dummy.buswidth;
This is a legitimate fix. The other 3 won't make much of a difference in
practice but are good changes regardless IMO.
Acked-by: Pratyush Yadav <p.yadav@ti.com>
>
> switch (width) {
> case SPI_NBITS_SINGLE:
> diff --git a/drivers/spi/spi-mtk-nor.c b/drivers/spi/spi-mtk-nor.c
> index 41e7b341d261..5c93730615f8 100644
> --- a/drivers/spi/spi-mtk-nor.c
> +++ b/drivers/spi/spi-mtk-nor.c
> @@ -160,7 +160,7 @@ static bool mtk_nor_match_read(const struct spi_mem_op *op)
> {
> int dummy = 0;
>
> - if (op->dummy.buswidth)
> + if (op->dummy.nbytes)
> dummy = op->dummy.nbytes * BITS_PER_BYTE / op->dummy.buswidth;
>
> if ((op->data.buswidth == 2) || (op->data.buswidth == 4)) {
> diff --git a/drivers/spi/spi-stm32-qspi.c b/drivers/spi/spi-stm32-qspi.c
> index 27f35aa2d746..514337c86d2c 100644
> --- a/drivers/spi/spi-stm32-qspi.c
> +++ b/drivers/spi/spi-stm32-qspi.c
> @@ -397,7 +397,7 @@ static int stm32_qspi_send(struct spi_mem *mem, const struct spi_mem_op *op)
> ccr |= FIELD_PREP(CCR_ADSIZE_MASK, op->addr.nbytes - 1);
> }
>
> - if (op->dummy.buswidth && op->dummy.nbytes)
> + if (op->dummy.nbytes)
> ccr |= FIELD_PREP(CCR_DCYC_MASK,
> op->dummy.nbytes * 8 / op->dummy.buswidth);
>
> --
> 2.33.0
--
Regards,
Pratyush Yadav
Texas Instruments Inc.
next prev parent reply other threads:[~2021-09-17 16:43 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-08 5:29 [PATCH] spi: Fixed division by zero warning Yoshitaka Ikeda
2021-09-08 6:17 ` Yoshitaka Ikeda
2021-09-17 16:42 ` Pratyush Yadav [this message]
2021-09-20 15:30 ` Mark Brown
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