linux-kernel - Re: [PATCH 3/3] drivers: remoteproc: add Versal and Versal-NET support

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Date: Tue, 19 Mar 2024 09:50:53 -0500
From: Tanmay Shah <tanmay.shah@....com>
To: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
 andersson@...nel.org, mathieu.poirier@...aro.org, robh+dt@...nel.org,
 krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
 michal.simek@....com, ben.levinsky@....com
Cc: linux-remoteproc@...r.kernel.org, devicetree@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] drivers: remoteproc: add Versal and Versal-NET
 support



On 3/19/24 12:25 AM, Krzysztof Kozlowski wrote:
> On 19/03/2024 02:06, Tanmay Shah wrote:
>> 
>> 
>> On 3/17/24 1:55 PM, Krzysztof Kozlowski wrote:
>>> On 15/03/2024 22:15, Tanmay Shah wrote:
>>>> AMD-Xilinx Versal and Versal-NET are successor of ZynqMP platform. ZynqMP
>>>> remoteproc driver is mostly compatible with new platforms except few
>>>> platform specific differences.
>>>>
>>>> Versal has same IP of cortex-R5 cores hence maintained compatible string
>>>> same as ZynqMP platform. However, hardcode TCM addresses are not
>>>> supported for new platforms and must be provided in device-tree as per
>>>> new bindings. This makes TCM representation data-driven and easy to
>>>> maintain. This check is provided in the driver.
>>>>
>>>> For Versal-NET platform, TCM doesn't need to be configured in lockstep
>>>> mode or split mode. Hence that call to PMC firmware is avoided in the
>>>> driver for Versal-NET platform.
>>>>
>>>> Signed-off-by: Tanmay Shah <tanmay.shah@....com>
>>>> ---
>>>>  drivers/remoteproc/xlnx_r5_remoteproc.c | 19 +++++++++++++++----
>>>>  1 file changed, 15 insertions(+), 4 deletions(-)
>>>>
>>>> diff --git a/drivers/remoteproc/xlnx_r5_remoteproc.c b/drivers/remoteproc/xlnx_r5_remoteproc.c
>>>> index d4a22caebaad..193bc159d1b4 100644
>>>> --- a/drivers/remoteproc/xlnx_r5_remoteproc.c
>>>> +++ b/drivers/remoteproc/xlnx_r5_remoteproc.c
>>>> @@ -323,9 +323,12 @@ static int zynqmp_r5_set_mode(struct zynqmp_r5_core *r5_core,
>>>>  		return ret;
>>>>  	}
>>>>  
>>>> -	ret = zynqmp_pm_set_tcm_config(r5_core->pm_domain_id, tcm_mode);
>>>> -	if (ret < 0)
>>>> -		dev_err(r5_core->dev, "failed to configure TCM\n");
>>>> +	/* TCM configuration is not needed in versal-net */
>>>> +	if (device_is_compatible(r5_core->dev, "xlnx,zynqmp-r5f")) {
>>>> +		ret = zynqmp_pm_set_tcm_config(r5_core->pm_domain_id, tcm_mode);
>>>> +		if (ret < 0)
>>>> +			dev_err(r5_core->dev, "failed to configure TCM\n");
>>>> +	}
>>>>  
>>>>  	return ret;
>>>>  }
>>>> @@ -933,10 +936,17 @@ static int zynqmp_r5_core_init(struct zynqmp_r5_cluster *cluster,
>>>>  	int ret, i;
>>>>  
>>>>  	r5_core = cluster->r5_cores[0];
>>>> +
>>>> +	/*
>>>> +	 * New platforms must use device tree for TCM parsing.
>>>> +	 * Only ZynqMP uses hardcode TCM.
>>>> +	 */
>>>>  	if (of_find_property(r5_core->np, "reg", NULL))
>>>>  		ret = zynqmp_r5_get_tcm_node_from_dt(cluster);
>>>> -	else
>>>> +	else if (of_machine_is_compatible("xlnx,zynqmp"))
>>>>  		ret = zynqmp_r5_get_tcm_node(cluster);
>>>
>>> That's poor code. Your drivers should not depend on platform. I don't
>>> understand why you need to do this and how is even related to this patch.
>> 
>> You are correct, ideally this shouldn't be needed. However, this driver contains
>> hardcode TCM addresses that were used before TCM bindings were designed and available in
>> device-tree. This check is provided to maintain backward compatibility with device-tree
>> where TCM isn't expected.
>> 
>> For new platforms (Versal and Versal-NET) TCM must be provided in device-tree and for
>> ZynqMP if it's not in device-tree then to maintain backward compatibility hardcode
>> addresses are used.
> 
> That does not work like this. You cannot bind to some sort of different
> compatible. If you disagree, please list the compatibles the driver
> binds to.

Okay understood. I believe then removing hardcode addresses makes more sense in that
case. So, driver will become same for all the devices.

> 
> Best regards,
> Krzysztof
>