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Date:   Wed, 1 Apr 2020 13:17:07 -0700
From:   Bjorn Andersson <bjorn.andersson@linaro.org>
To:     Rishabh Bhatnagar <rishabhb@codeaurora.org>
Cc:     linux-kernel@vger.kernel.org, linux-remoteproc@vger.kernel.org,
        psodagud@codeaurora.org, tsoni@codeaurora.org,
        sidgup@codeaurora.org
Subject: Re: [PATCH 1/2] remoteproc: qcom: Add bus scaling capability during
 bootup
Message-ID: <20200401201707.GG267644@minitux>
References: <1585357147-4616-1-git-send-email-rishabhb@codeaurora.org>
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On Fri 27 Mar 17:59 PDT 2020, Rishabh Bhatnagar wrote:

> During bootup since remote processors cannot request for
> additional bus bandwidth from the interconect framework,
> platform driver should provide the proxy resources. This
> is useful for scenarios where the Q6 tries to access the DDR
> memory in the initial stages of bootup. For e.g. during
> bootup or after recovery modem Q6 tries to zero out the bss
> section in the DDR. Since this is a big chunk of memory if
> don't bump up the bandwidth we might encounter timeout issues.
> This patch makes a proxy vote for maximizing the bus bandwidth
> during bootup and removes it once processor is up.
> 
> Signed-off-by: Rishabh Bhatnagar <rishabhb@codeaurora.org>
> ---
>  drivers/remoteproc/qcom_q6v5_pas.c | 43 +++++++++++++++++++++++++++++++++++++-
>  1 file changed, 42 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/remoteproc/qcom_q6v5_pas.c b/drivers/remoteproc/qcom_q6v5_pas.c
> index edf9d0e..8f5db8d 100644
> --- a/drivers/remoteproc/qcom_q6v5_pas.c
> +++ b/drivers/remoteproc/qcom_q6v5_pas.c
> @@ -20,6 +20,7 @@
>  #include <linux/qcom_scm.h>
>  #include <linux/regulator/consumer.h>
>  #include <linux/remoteproc.h>
> +#include <linux/interconnect.h>

These are sorted alphabetically, please maintain this.

>  #include <linux/soc/qcom/mdt_loader.h>
>  #include <linux/soc/qcom/smem.h>
>  #include <linux/soc/qcom/smem_state.h>
> @@ -28,6 +29,9 @@
>  #include "qcom_q6v5.h"
>  #include "remoteproc_internal.h"
>  
> +#define PIL_TZ_AVG_BW  0
> +#define PIL_TZ_PEAK_BW UINT_MAX

Please just inline these in do_bus_scaling().

> +
>  struct adsp_data {
>  	int crash_reason_smem;
>  	const char *firmware_name;
> @@ -62,6 +66,7 @@ struct qcom_adsp {
>  	int proxy_pd_count;
>  
>  	int pas_id;
> +	struct icc_path *bus_client;

Please rename this proxy_path

>  	int crash_reason_smem;
>  	bool has_aggre2_clk;
>  
> @@ -124,6 +129,25 @@ static int adsp_load(struct rproc *rproc, const struct firmware *fw)
>  
>  }
>  
> +static int do_bus_scaling(struct qcom_adsp *adsp, bool enable)

adsp_bus_vote()

> +{
> +	int rc;

This driver uses "int ret".

> +	u32 avg_bw = enable ? PIL_TZ_AVG_BW : 0;

No need to carry a variable for 0 or 0, jut pass 0 in the function call
directly.

> +	u32 peak_bw = enable ? PIL_TZ_PEAK_BW : 0;
> +
> +	if (adsp->bus_client) {

No need for this check, icc_set_bw(NULL, ..) is a nop.

> +		rc = icc_set_bw(adsp->bus_client, avg_bw, peak_bw);
> +		if (rc) {
> +			dev_err(adsp->dev, "bandwidth request failed(rc:%d)\n",

"failed to request bandwidth: %d\n"

> +				rc);
> +			return rc;
> +		}
> +	} else
> +		dev_info(adsp->dev, "Bus scaling not setup for %s\n",

No need to print this.

> +			adsp->rproc->name);
> +	return 0;
> +}
> +
>  static int adsp_start(struct rproc *rproc)
>  {
>  	struct qcom_adsp *adsp = (struct qcom_adsp *)rproc->priv;
> @@ -131,9 +155,13 @@ static int adsp_start(struct rproc *rproc)
>  
>  	qcom_q6v5_prepare(&adsp->q6v5);
>  
> +	ret = do_bus_scaling(adsp, true);
> +	if (ret)
> +		goto disable_irqs;
> +
>  	ret = adsp_pds_enable(adsp, adsp->active_pds, adsp->active_pd_count);
>  	if (ret < 0)
> -		goto disable_irqs;
> +		goto unscale_bus;
>  
>  	ret = adsp_pds_enable(adsp, adsp->proxy_pds, adsp->proxy_pd_count);
>  	if (ret < 0)
> @@ -183,6 +211,8 @@ static int adsp_start(struct rproc *rproc)
>  	adsp_pds_disable(adsp, adsp->proxy_pds, adsp->proxy_pd_count);
>  disable_active_pds:
>  	adsp_pds_disable(adsp, adsp->active_pds, adsp->active_pd_count);
> +unscale_bus:
> +	do_bus_scaling(adsp, false);
>  disable_irqs:
>  	qcom_q6v5_unprepare(&adsp->q6v5);
>  
> @@ -198,6 +228,7 @@ static void qcom_pas_handover(struct qcom_q6v5 *q6v5)
>  	clk_disable_unprepare(adsp->aggre2_clk);
>  	clk_disable_unprepare(adsp->xo);
>  	adsp_pds_disable(adsp, adsp->proxy_pds, adsp->proxy_pd_count);
> +	do_bus_scaling(adsp, false);
>  }
>  
>  static int adsp_stop(struct rproc *rproc)
> @@ -280,6 +311,14 @@ static int adsp_init_regulator(struct qcom_adsp *adsp)
>  	return PTR_ERR_OR_ZERO(adsp->px_supply);
>  }
>  
> +static void adsp_init_bus_scaling(struct qcom_adsp *adsp)
> +{
> +	adsp->bus_client = of_icc_get(adsp->dev, NULL);
> +	if (!adsp->bus_client)

!adsp->bus_client means there's no interconnects property in the DT
node, you still need to test for errors with IS_ERR().

And in particular you're not guaranteed that the provider has probed, so
you need to propagate EPROBE_DEFER.

> +		dev_warn(adsp->dev, "%s: unable to get bus client \n",
> +			__func__);

This is a dev_err() for the case of IS_ERR().

And please drop the __func__, it doesn't add any value.

> +}
> +
>  static int adsp_pds_attach(struct device *dev, struct device **devs,
>  			   char **pd_names)
>  {
> @@ -410,6 +449,8 @@ static int adsp_probe(struct platform_device *pdev)
>  	if (ret)
>  		goto free_rproc;
>  
> +	adsp_init_bus_scaling(adsp);
> +

As stated above, you need to propagate actual errors here (i.e. not the
case where of_icc_get() returned NULL, but when it returned IS_ERR())

Regards,
bjorn
>  	ret = adsp_pds_attach(&pdev->dev, adsp->active_pds,
>  			      desc->active_pd_names);
>  	if (ret < 0)
> -- 
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