Re: [PATCH v3 16/17] crypto: qce: Defer probing if BAM dma channel is not yet initialized

[Thara Gopinath <thara.gopinath@linaro.org>]

On 5/19/21 10:36 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.

So, I do not understand what issue you faced with the current code 
ordering. When bam dma is not initialized, qce_dma_request will fail and
rest the error path kicks in.
To me the correct ordering for enabling a driver is to turn on clocks 
and interconnect before requesting for dma. Unless, there is a specific 
issue, I will ask for that order to be maintained.

Warm Regards
Thara

> 
> Cc: Thara Gopinath <thara.gopinath@linaro.org>
> Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
> Cc: Rob Herring <robh+dt@kernel.org>
> Cc: Andy Gross <agross@kernel.org>
> Cc: Herbert Xu <herbert@gondor.apana.org.au>
> Cc: David S. Miller <davem@davemloft.net>
> Cc: Stephen Boyd <sboyd@kernel.org>
> Cc: Michael Turquette <mturquette@baylibre.com>
> Cc: Vinod Koul <vkoul@kernel.org>
> Cc: dmaengine@vger.kernel.org
> Cc: linux-clk@vger.kernel.org
> Cc: linux-crypto@vger.kernel.org
> Cc: devicetree@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> Cc: bhupesh.linux@gmail.com
> Signed-off-by: Bhupesh Sharma <bhupesh.sharma@linaro.org>
> ---
>   drivers/crypto/qce/core.c | 16 +++++++++-------
>   1 file changed, 9 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/crypto/qce/core.c b/drivers/crypto/qce/core.c
> index 8b3e2b4580c2..207221d5b996 100644
> --- a/drivers/crypto/qce/core.c
> +++ b/drivers/crypto/qce/core.c
> @@ -218,6 +218,14 @@ static int qce_crypto_probe(struct platform_device *pdev)
>   	if (ret < 0)
>   		goto err_out;
>   
> +	/* 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 = devm_of_icc_get(qce->dev, "memory");
>   	if (IS_ERR(qce->mem_path))
>   		return dev_err_probe(dev, PTR_ERR(qce->mem_path),
> @@ -269,10 +277,6 @@ static int qce_crypto_probe(struct platform_device *pdev)
>   			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;
> @@ -287,12 +291,10 @@ 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:
>