linux-kernel - Re: [PATCH v4 18/20] crypto: qce: Defer probing if BAM dma channel is not yet initialized

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Message-ID: <c6df4da4-3d50-5592-1036-b9a8cebb79d9@linaro.org>
Date:   Wed, 20 Oct 2021 10:10:39 -0400
From:   Thara Gopinath <thara.gopinath@...aro.org>
To:     Bhupesh Sharma <bhupesh.sharma@...aro.org>,
        linux-arm-msm@...r.kernel.org, linux-crypto@...r.kernel.org
Cc:     bhupesh.linux@...il.com, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, robh+dt@...nel.org, agross@...nel.org,
        herbert@...dor.apana.org.au, davem@...emloft.net,
        Bjorn Andersson <bjorn.andersson@...aro.org>
Subject: Re: [PATCH v4 18/20] crypto: qce: Defer probing if BAM dma channel is
 not yet initialized



On 10/13/21 6:55 AM, Bhupesh Sharma wrote:
> Since the Qualcomm qce crypto driver needs the BAM dma driver to be
> setup first (to allow crypto operations), it makes sense to defer
> the qce crypto driver probing in case the BAM dma driver is not yet
> probed.
> 
> Move the code leg requesting dma channels earlier in the
> probe() flow. This fixes the qce probe failure issues when both qce
> and BMA dma are compiled as static part of the kernel.

Hi Bhupesh,

I am quite curious to know the nature of probe failure you are seeing 
with the current sequence.  I am not against changing the sequence but 
for me when a driver is enabled, it is clocks first, interconnect next 
and then dma. Also I have tested the current sequence on sm8150 with 
both the modules built in as static and I have not seen the failure.

-- 
Warm Regards
Thara (She/Her/Hers)
> 
> Cc: Thara Gopinath <thara.gopinath@...aro.org>
> Cc: Bjorn Andersson <bjorn.andersson@...aro.org>
> Signed-off-by: Bhupesh Sharma <bhupesh.sharma@...aro.org>
> ---
>   drivers/crypto/qce/core.c | 20 ++++++++++++--------
>   1 file changed, 12 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/crypto/qce/core.c b/drivers/crypto/qce/core.c
> index cb8c77709e1e..c6f686126fc9 100644
> --- a/drivers/crypto/qce/core.c
> +++ b/drivers/crypto/qce/core.c
> @@ -209,9 +209,19 @@ static int qce_crypto_probe(struct platform_device *pdev)
>   	if (ret < 0)
>   		return ret;
>   
> +	/* qce driver requires BAM dma driver to be setup first.
> +	 * In case the dma channel are not set yet, this check
> +	 * helps use to return -EPROBE_DEFER earlier.
> +	 */
> +	ret = qce_dma_request(qce->dev, &qce->dma);
> +	if (ret)
> +		return ret;
> +
>   	qce->mem_path = of_icc_get(qce->dev, "memory");
> -	if (IS_ERR(qce->mem_path))
> +	if (IS_ERR(qce->mem_path)) {
> +		qce_dma_release(&qce->dma);
>   		return PTR_ERR(qce->mem_path);
> +	}
>   
>   	qce->core = devm_clk_get_optional(qce->dev, "core");
>   	if (IS_ERR(qce->core)) {
> @@ -247,10 +257,6 @@ static int qce_crypto_probe(struct platform_device *pdev)
>   	if (ret)
>   		goto err_clks_iface;
>   
> -	ret = qce_dma_request(qce->dev, &qce->dma);
> -	if (ret)
> -		goto err_clks;
> -
>   	ret = qce_check_version(qce);
>   	if (ret)
>   		goto err_clks;
> @@ -265,12 +271,10 @@ static int qce_crypto_probe(struct platform_device *pdev)
>   
>   	ret = qce_register_algs(qce);
>   	if (ret)
> -		goto err_dma;
> +		goto err_clks;
>   
>   	return 0;
>   
> -err_dma:
> -	qce_dma_release(&qce->dma);
>   err_clks:
>   	clk_disable_unprepare(qce->bus);
>   err_clks_iface:
>