netdev - Re: [EXTERNAL] Re: [PATCH v3 5/6] soc: ti: pruss: Add helper function to enable OCP master ports

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Date:   Thu, 9 Mar 2023 17:04:50 +0530
From:   Md Danish Anwar <a0501179@...com>
To:     Tony Lindgren <tony@...mide.com>,
        MD Danish Anwar <danishanwar@...com>
CC:     "Andrew F. Davis" <afd@...com>, Suman Anna <s-anna@...com>,
        Roger Quadros <rogerq@...nel.org>,
        Vignesh Raghavendra <vigneshr@...com>,
        Tero Kristo <t-kristo@...com>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        "Bjorn Andersson" <andersson@...nel.org>,
        Santosh Shilimkar <ssantosh@...nel.org>,
        Nishanth Menon <nm@...com>, <linux-remoteproc@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <linux-omap@...r.kernel.org>,
        <srk@...com>, <devicetree@...r.kernel.org>,
        <netdev@...r.kernel.org>
Subject: Re: [EXTERNAL] Re: [PATCH v3 5/6] soc: ti: pruss: Add helper function
 to enable OCP master ports

Hi Tony,

On 09/03/23 12:34, Tony Lindgren wrote:
> Hi,
> 
> * MD Danish Anwar <danishanwar@...com> [230306 11:10]:
>> From: Suman Anna <s-anna@...com>
>> +/**
>> + * pruss_cfg_ocp_master_ports() - configure PRUSS OCP master ports
>> + * @pruss: the pruss instance handle
>> + * @enable: set to true for enabling or false for disabling the OCP master ports
>> + *
>> + * This function programs the PRUSS_SYSCFG.STANDBY_INIT bit either to enable or
>> + * disable the OCP master ports (applicable only on SoCs using OCP interconnect
>> + * like the OMAP family). Clearing the bit achieves dual functionalities - one
>> + * is to deassert the MStandby signal to the device PRCM, and the other is to
>> + * enable OCP master ports to allow accesses outside of the PRU-ICSS. The
>> + * function has to wait for the PRCM to acknowledge through the monitoring of
>> + * the PRUSS_SYSCFG.SUB_MWAIT bit when enabling master ports. Setting the bit
>> + * disables the master access, and also signals the PRCM that the PRUSS is ready
>> + * for Standby.
>> + *
>> + * Return: 0 on success, or an error code otherwise. ETIMEDOUT is returned
>> + * when the ready-state fails.
>> + */
>> +int pruss_cfg_ocp_master_ports(struct pruss *pruss, bool enable)
>> +{
>> +	int ret;
>> +	u32 syscfg_val, i;
>> +	const struct pruss_private_data *data;
>> +
>> +	if (IS_ERR_OR_NULL(pruss))
>> +		return -EINVAL;
>> +
>> +	data = of_device_get_match_data(pruss->dev);
>> +
>> +	/* nothing to do on non OMAP-SoCs */
>> +	if (!data || !data->has_ocp_syscfg)
>> +		return 0;
>> +
>> +	/* assert the MStandby signal during disable path */
>> +	if (!enable)
>> +		return pruss_cfg_update(pruss, PRUSS_CFG_SYSCFG,
>> +					SYSCFG_STANDBY_INIT,
>> +					SYSCFG_STANDBY_INIT);
>> +
>> +	/* enable the OCP master ports and disable MStandby */
>> +	ret = pruss_cfg_update(pruss, PRUSS_CFG_SYSCFG, SYSCFG_STANDBY_INIT, 0);
>> +	if (ret)
>> +		return ret;
>> +
>> +	/* wait till we are ready for transactions - delay is arbitrary */
>> +	for (i = 0; i < 10; i++) {
>> +		ret = pruss_cfg_read(pruss, PRUSS_CFG_SYSCFG, &syscfg_val);
>> +		if (ret)
>> +			goto disable;
>> +
>> +		if (!(syscfg_val & SYSCFG_SUB_MWAIT_READY))
>> +			return 0;
>> +
>> +		udelay(5);
>> +	}
>> +
>> +	dev_err(pruss->dev, "timeout waiting for SUB_MWAIT_READY\n");
>> +	ret = -ETIMEDOUT;
>> +
>> +disable:
>> +	pruss_cfg_update(pruss, PRUSS_CFG_SYSCFG, SYSCFG_STANDBY_INIT,
>> +			 SYSCFG_STANDBY_INIT);
>> +	return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(pruss_cfg_ocp_master_ports);
> 
> The above you should no longer be needed, see for example am33xx-l4.dtsi
> for pruss_tm: target-module@...000. The SYSCFG register is managed by
> drivers/bus/ti-sysc.c using compatible "ti,sysc-pruss", and the "sysc"
> reg-names property. So when any of the child devices do pm_runtime_get()
> related functions, the PRUSS top level interconnect target module is
> automatically enabled and disabled as needed.
> 
> If there's something still missing like dts configuration for some SoCs,
> or quirk handling in ti-sysc.c, let's fix those instead so we can avoid
> exporting a custom function for pruss_cfg_ocp_master_ports.
> 
> Regards,
> 
> Tony

I will remove this patch in the next revision of this series as it is no longer
needed.

-- 
Thanks and Regards,
Danish.