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References: <20221115162654.2016820-1-frieder@fris.de>
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From:   Fabio Estevam <festevam@gmail.com>
Date:   Tue, 15 Nov 2022 14:24:24 -0300
Message-ID: <CAOMZO5BEYhGS-nRuiTr6veujLM=k7bP9hHHCy6X62hfFzyLh_A@mail.gmail.com>
Subject: Re: [PATCH v2] spi: spi-imx: Fix spi_bus_clk if requested clock is
 higher than input clock
To:     Frieder Schrempf <frieder@fris.de>
Cc:     David Jander <david@protonic.nl>,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        linux-spi@vger.kernel.org, Marc Kleine-Budde <mkl@pengutronix.de>,
        Mark Brown <broonie@kernel.org>,
        Sascha Hauer <s.hauer@pengutronix.de>,
        Shawn Guo <shawnguo@kernel.org>,
        Frieder Schrempf <frieder.schrempf@kontron.de>,
        Marek Vasut <marex@denx.de>, stable@vger.kernel.org,
        Baruch Siach <baruch.siach@siklu.com>,
        Minghao Chi <chi.minghao@zte.com.cn>,
        NXP Linux Team <linux-imx@nxp.com>,
        Pengutronix Kernel Team <kernel@pengutronix.de>
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On Tue, Nov 15, 2022 at 1:27 PM Frieder Schrempf <frieder@fris.de> wrote:
>
> From: Frieder Schrempf <frieder.schrempf@kontron.de>
>
> In case the requested bus clock is higher than the input clock, the correct
> dividers (pre = 0, post = 0) are returned from mx51_ecspi_clkdiv(), but
> *fres is left uninitialized and therefore contains an arbitrary value.
>
> This causes trouble for the recently introduced PIO polling feature as the
> value in spi_imx->spi_bus_clk is used there to calculate for which
> transfers to enable PIO polling.
>
> Fix this by setting *fres even if no clock dividers are in use.
>
> This issue was observed on Kontron BL i.MX8MM with an SPI peripheral clock set
> to 50 MHz by default and a requested SPI bus clock of 80 MHz for the SPI NOR
> flash.
>
> With the fix applied the debug message from mx51_ecspi_clkdiv() now prints the
> following:
>
> spi_imx 30820000.spi: mx51_ecspi_clkdiv: fin: 50000000, fspi: 50000000,
> post: 0, pre: 0
>
> Fixes: 07e759387788 ("spi: spi-imx: add PIO polling support")
> Cc: Marc Kleine-Budde <mkl@pengutronix.de>
> Cc: David Jander <david@protonic.nl>
> Cc: Fabio Estevam <festevam@gmail.com>
> Cc: Mark Brown <broonie@kernel.org>
> Cc: Marek Vasut <marex@denx.de>
> Cc: stable@vger.kernel.org
> Signed-off-by: Frieder Schrempf <frieder.schrempf@kontron.de>

Thanks for the fix:

Tested-by: Fabio Estevam <festevam@gmail.com>