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From: Alexandre TORGUE <alexandre.torgue@foss.st.com>
To: Marek Vasut <marex@denx.de>, <linux-arm-kernel@lists.infradead.org>
Cc: Patrice Chotard <patrice.chotard@foss.st.com>,
	Patrick Delaunay <patrick.delaunay@foss.st.com>,
	<linux-stm32@st-md-mailman.stormreply.com>
Subject: Re: [PATCH] ARM: dts: stm32: Reduce DHCOR SPI NOR frequency to 50 MHz
Date: Mon, 20 Sep 2021 09:39:29 +0200	[thread overview]
Message-ID: <a6bbc8bc-a5ae-2a3a-e352-936b4ba6ecc3@foss.st.com> (raw)
In-Reply-To: <20210809121324.155219-1-marex@denx.de>

Hi Marek

On 8/9/21 2:13 PM, Marek Vasut wrote:
> The SPI NOR is a bit further away from the SoC on DHCOR than on DHCOM,
> which causes additional signal delay. At 108 MHz, this delay triggers
> a sporadic issue where the first bit of RX data is not received by the
> QSPI controller.
> 
> There are two options of addressing this problem, either by using the
> DLYB block to compensate the extra delay, or by reducing the QSPI bus
> clock frequency. The former requires calibration and that is overly
> complex, so opt for the second option.
> 
> Fixes: 76045bc457104 ("ARM: dts: stm32: Add QSPI NOR on AV96")
> Signed-off-by: Marek Vasut <marex@denx.de>
> Cc: Alexandre Torgue <alexandre.torgue@foss.st.com>
> Cc: Patrice Chotard <patrice.chotard@foss.st.com>
> Cc: Patrick Delaunay <patrick.delaunay@foss.st.com>
> Cc: linux-stm32@st-md-mailman.stormreply.com
> To: linux-arm-kernel@lists.infradead.org
> ---
>   arch/arm/boot/dts/stm32mp15xx-dhcor-som.dtsi | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/arm/boot/dts/stm32mp15xx-dhcor-som.dtsi b/arch/arm/boot/dts/stm32mp15xx-dhcor-som.dtsi
> index 2b0ac605549d7..44ecc47085871 100644
> --- a/arch/arm/boot/dts/stm32mp15xx-dhcor-som.dtsi
> +++ b/arch/arm/boot/dts/stm32mp15xx-dhcor-som.dtsi
> @@ -202,7 +202,7 @@ flash0: flash@0 {
>   		compatible = "jedec,spi-nor";
>   		reg = <0>;
>   		spi-rx-bus-width = <4>;
> -		spi-max-frequency = <108000000>;
> +		spi-max-frequency = <50000000>;
>   		#address-cells = <1>;
>   		#size-cells = <1>;
>   	};
> 

Applied on stm32-next.

Thanks
Alex

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  reply	other threads:[~2021-09-20  7:41 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-09 12:13 [PATCH] ARM: dts: stm32: Reduce DHCOR SPI NOR frequency to 50 MHz Marek Vasut
2021-09-20  7:39 ` Alexandre TORGUE [this message]
  -- strict thread matches above, loose matches on Subject: below --
2021-08-09 12:06 Marek Vasut
2021-08-09 12:33 ` Patrice CHOTARD
2021-08-16 11:29   ` Patrice CHOTARD

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