Re: [PATCH v3 09/13] spi: cadence-quadspi: reject 2-byte-address DDR ops on PHY-tunable hardware

From: Miquel Raynal <miquel.raynal@bootlin.com>
To: Santhosh Kumar K <s-k6@ti.com>
Cc: <broonie@kernel.org>,  <robh@kernel.org>,  <krzk+dt@kernel.org>,
	<conor+dt@kernel.org>,  <richard@nod.at>,  <vigneshr@ti.com>,
	<pratyush@kernel.org>,  <mwalle@kernel.org>,
	<takahiro.kuwano@infineon.com>,  <linux-spi@vger.kernel.org>,
	<devicetree@vger.kernel.org>,  <linux-kernel@vger.kernel.org>,
	<linux-mtd@lists.infradead.org>,  <praneeth@ti.com>,
	 <u-kumar1@ti.com>, <a-dutta@ti.com>
Subject: Re: [PATCH v3 09/13] spi: cadence-quadspi: reject 2-byte-address DDR ops on PHY-tunable hardware
Date: Thu, 28 May 2026 11:01:19 +0200	[thread overview]
Message-ID: <87y0h3gb6o.fsf@bootlin.com> (raw)
In-Reply-To: <20260527175527.2247679-10-s-k6@ti.com> (Santhosh Kumar K.'s message of "Wed, 27 May 2026 23:25:23 +0530")

On 27/05/2026 at 23:25:23 +0530, Santhosh Kumar K <s-k6@ti.com> wrote:

> Erratum i2383 affects the AM654 OSPI controller: in PHY DDR mode,
> operations with a 2-byte address cause an internal state machine to
> mis-compare the transmitted address byte count against 1 instead of 2,
> locking up the address phase. [0]
>
> Add a CQSPI_NO_2BYTE_ADDR_PHY_DDR quirk flag and set it on the am654_ospi
> platform data. In cqspi_supports_mem_op(), when a controller carries this
> quirk and has PHY tuning support, reject DDR operations that use 2-byte
> addressing.
>
> [0] https://www.ti.com/lit/er/sprz544c/sprz544c.pdf
>
> Signed-off-by: Santhosh Kumar K <s-k6@ti.com>
> ---
>  drivers/spi/spi-cadence-quadspi.c | 15 ++++++++++++++-
>  1 file changed, 14 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/spi/spi-cadence-quadspi.c b/drivers/spi/spi-cadence-quadspi.c
> index 508bc5bc4ab5..72208d376305 100644
> --- a/drivers/spi/spi-cadence-quadspi.c
> +++ b/drivers/spi/spi-cadence-quadspi.c
> @@ -49,6 +49,7 @@ static_assert(CQSPI_MAX_CHIPSELECT <= SPI_DEVICE_CS_CNT_MAX);
>  #define CQSPI_DISABLE_RUNTIME_PM	BIT(10)
>  #define CQSPI_NO_INDIRECT_MODE		BIT(11)
>  #define CQSPI_HAS_WR_PROTECT		BIT(12)
> +#define CQSPI_NO_2BYTE_ADDR_PHY_DDR	BIT(13)
>  
>  /* Capabilities */
>  #define CQSPI_SUPPORTS_OCTAL		BIT(0)
> @@ -1627,6 +1628,18 @@ static bool cqspi_supports_mem_op(struct spi_mem *mem,
>  		if (op->data.nbytes && op->data.buswidth != 8)
>  			return false;
>  
> +		/*
> +		 * Erratum i2383: In PHY DDR mode, 2-byte addressing causes an
> +		 * internal state machine to mis-compare the transmitted
> +		 * address byte count against 1 instead of 2, locking up the
> +		 * address phase. Reject such ops on controllers that need it.
> +		 */
> +		if (cqspi->ddata &&
> +		    (cqspi->ddata->quirks & CQSPI_NO_2BYTE_ADDR_PHY_DDR)) {
> +			if (op->addr.nbytes == 2 && cqspi->ddata->execute_tuning)
> +				return false;
> +		}

I don't think this is a valid approach. What we want is to prevent
tuning in octal DTR mode with 2 bytes addressing, instead of preventing
reads/writes in octal DTR modes after tuning. Have you tried on an AM62A LP
SK? I bet probe fails..

The quirk should be handled at the beginning of the tuning procedure, so
we skip tuning entirely in this case.

Thanks,
Miquèl