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Message-ID: <a9901cbd-8af3-04aa-12f5-df7c563f873a@linaro.org>
Date:   Wed, 9 Nov 2022 12:20:38 +0100
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Subject: Re: [PATCH v2 5/6] can: m_can: Add ECC functionality for message RAM
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To:     Vivek Yadav <vivek.2311@samsung.com>, rcsekar@samsung.com,
        krzysztof.kozlowski+dt@linaro.org, wg@grandegger.com,
        mkl@pengutronix.de, davem@davemloft.net, edumazet@google.com,
        kuba@kernel.org, pabeni@redhat.com, pankaj.dubey@samsung.com,
        ravi.patel@samsung.com, alim.akhtar@samsung.com,
        linux-fsd@tesla.com, robh+dt@kernel.org
Cc:     linux-can@vger.kernel.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-samsung-soc@vger.kernel.org, devicetree@vger.kernel.org,
        aswani.reddy@samsung.com, sriranjani.p@samsung.com
References: <20221109100928.109478-1-vivek.2311@samsung.com>
 <CGME20221109100302epcas5p276282a3a320649661939dcb893765fbf@epcas5p2.samsung.com>
 <20221109100928.109478-6-vivek.2311@samsung.com>
From:   Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
In-Reply-To: <20221109100928.109478-6-vivek.2311@samsung.com>
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Precedence: bulk

On 09/11/2022 11:09, Vivek Yadav wrote:
> Whenever MCAN Buffers and FIFOs are stored on message ram, there are
> inherent risks of corruption known as single-bit errors.
> 
> Enable error correction code (ECC) data integrity check for Message RAM
> to create valid ECC checksums.
> 
> ECC uses a respective number of bits, which are added to each word as a
> parity and that will raise the error signal on the corruption in the
> Interrupt Register(IR).
> 
> This indicates either bit error detected and Corrected(BEC) or No bit
> error detected when reading from Message RAM.
> 
> Signed-off-by: Chandrasekar R <rcsekar@samsung.com>
> Signed-off-by: Vivek Yadav <vivek.2311@samsung.com>

(...)

>  
> +static int m_can_plat_init(struct m_can_classdev *cdev)
> +{
> +	struct  m_can_ecc_regmap *ecc_cfg = &cdev->ecc_cfg_sys;
> +	struct device_node *np = cdev->dev->of_node;
> +	int ret = 0;
> +
> +	if (cdev->mram_cfg_flag != ECC_ENABLE) {
> +		/* Initialize mcan message ram */
> +		ret = m_can_init_ram(cdev);
> +
> +		if (ret)
> +			return ret;
> +
> +		cdev->mram_cfg_flag = ECC_ENABLE;
> +	}
> +
> +	if (ecc_cfg->ecc_cfg_flag != ECC_ENABLE) {
> +		/* configure error code check for mram */
> +		if (!ecc_cfg->syscon) {
> +			ecc_cfg->syscon =
> +			syscon_regmap_lookup_by_phandle_args(np,
> +							     "tesla,mram-ecc-cfg"
> +							     , 1,

, goes to previous line

> +							     &ecc_cfg->reg);
> +		}
> +
> +		if (IS_ERR(ecc_cfg->syscon)) {
> +			dev_err(cdev->dev, "couldn't get the syscon reg!\n");

Didn't you just break all platforms using ECC?

Best regards,
Krzysztof