Re: [PATCH v26 5/5] remoteproc: Add initial zynqmp R5 remoteproc driver

[Mathieu Poirier]

On Mon, Mar 15, 2021 at 09:32:40PM +0000, Ben Levinsky wrote:
> 
> 
> -----Original Message-----
> From: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
> Date: Monday, March 15, 2021 at 10:37 AM
> To: Ben Levinsky <BLEVINSK@xxxxxxxxxx>
> Cc: "devicetree@xxxxxxxxxxxxxxx" <devicetree@xxxxxxxxxxxxxxx>, "linux-remoteproc@xxxxxxxxxxxxxxx" <linux-remoteproc@xxxxxxxxxxxxxxx>, "linux-kernel@xxxxxxxxxxxxxxx" <linux-kernel@xxxxxxxxxxxxxxx>, "linux-arm-kernel@xxxxxxxxxxxxxxxxxxx" <linux-arm-kernel@xxxxxxxxxxxxxxxxxxx>, Michal Simek <michals@xxxxxxxxxx>, "Ed T. Mooring" <emooring@xxxxxxxxxx>
> Subject: Re: [PATCH v26 5/5] remoteproc: Add initial zynqmp R5 remoteproc driver
> 
>     On Thu, Mar 11, 2021 at 11:49:13PM +0000, Ben Levinsky wrote:
>     > Hi Mathieu
>     > 
>     > -----Original Message-----
>     > From: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
>     > Date: Tuesday, March 9, 2021 at 8:53 AM
>     > To: Ben Levinsky <BLEVINSK@xxxxxxxxxx>
>     > Cc: "devicetree@xxxxxxxxxxxxxxx" <devicetree@xxxxxxxxxxxxxxx>, "linux-remoteproc@xxxxxxxxxxxxxxx" <linux-remoteproc@xxxxxxxxxxxxxxx>, "linux-kernel@xxxxxxxxxxxxxxx" <linux-kernel@xxxxxxxxxxxxxxx>, "linux-arm-kernel@xxxxxxxxxxxxxxxxxxx" <linux-arm-kernel@xxxxxxxxxxxxxxxxxxx>, Michal Simek <michals@xxxxxxxxxx>
>     > Subject: Re: [PATCH v26 5/5] remoteproc: Add initial zynqmp R5 remoteproc driver
>     > 
>     >     [...]
>     > 
>     >     > +
>     >     > +/**
>     >     > + * zynqmp_r5_probe - Probes ZynqMP R5 processor device node
>     >     > + *		       this is called for each individual R5 core to
>     >     > + *		       set up mailbox, Xilinx platform manager unique ID,
>     >     > + *		       add to rproc core
>     >     > + *
>     >     > + * @pdev: domain platform device for current R5 core
>     >     > + * @node: pointer of the device node for current R5 core
>     >     > + * @rpu_mode: mode to configure RPU, split or lockstep
>     >     > + *
>     >     > + * Return: 0 for success, negative value for failure.
>     >     > + */
>     >     > +static struct zynqmp_r5_rproc *zynqmp_r5_probe(struct platform_device *pdev,
>     >     > +					       struct device_node *node,
>     >     > +					       enum rpu_oper_mode rpu_mode)
>     >     > +{
>     >     > +	int ret, num_banks;
>     >     > +	struct device *dev = &pdev->dev;
>     >     > +	struct rproc *rproc_ptr;
>     >     > +	struct zynqmp_r5_rproc *z_rproc;
>     >     > +	struct device_node *r5_node;
>     >     > +
>     >     > +	/* Allocate remoteproc instance */
>     >     > +	rproc_ptr = devm_rproc_alloc(dev, dev_name(dev), &zynqmp_r5_rproc_ops,
>     >     > +				     NULL, sizeof(struct zynqmp_r5_rproc));
>     >     > +	if (!rproc_ptr) {
>     >     > +		ret = -ENOMEM;
>     >     > +		goto error;
>     >     > +	}
>     >     > +
>     >     > +	rproc_ptr->auto_boot = false;
>     >     > +	z_rproc = rproc_ptr->priv;
>     >     > +	z_rproc->rproc = rproc_ptr;
>     >     > +	r5_node = z_rproc->rproc->dev.parent->of_node;
>     >     > +
>     >     > +	/* Set up DMA mask */
>     >     > +	ret = dma_set_coherent_mask(dev, DMA_BIT_MASK(32));
>     >     > +	if (ret)
>     >     > +		goto error;
>     >     > +
>     >     > +	/* Get R5 power domain node */
>     >     > +	ret = of_property_read_u32(node, "power-domain", &z_rproc->pnode_id);
>     >     > +	if (ret)
>     >     > +		goto error;
>     >     > +
>     >     > +	ret = r5_set_mode(z_rproc, rpu_mode);
>     >     > +	if (ret)
>     >     > +		goto error;
>     >     > +
>     >     > +	if (of_property_read_bool(node, "mboxes")) {
>     >     > +		ret = zynqmp_r5_setup_mbox(z_rproc, node);
>     >     > +		if (ret)
>     >     > +			goto error;
>     >     > +	}
>     >     > +
>     >     > +	/* go through TCM banks for r5 node */
>     >     > +	num_banks = of_count_phandle_with_args(r5_node, BANK_LIST_PROP, NULL);
>     >     > +	if (num_banks <= 0) {
>     >     > +		dev_err(dev, "need to specify TCM banks\n");
>     >     > +		ret = -EINVAL;
>     >     > +		goto error;
>     >     > +	}
>     >     > +
>     >     > +	if (num_banks > NUM_SRAMS) {
>     >     > +		dev_err(dev, "max number of srams is %d. given: %d \r\n",
>     >     > +			NUM_SRAMS, num_banks);
>     >     > +		ret = -EINVAL;
>     >     > +		goto error;
>     >     > +	}
>     >     > +
>     >     > +	/* construct collection of srams used by the current R5 core */
>     >     > +	for (; num_banks; num_banks--) {
>     >     > +		struct resource rsc;
>     >     > +		struct device_node *dt_node;
>     >     > +		resource_size_t size;
>     >     > +		int i;
>     >     > +
>     >     > +		dt_node = of_parse_phandle(r5_node, BANK_LIST_PROP, i);
>     > 
>     >     Variable @i is not initialised but it is used as an index to retrieve a handle
>     >     to the sram banks.  That code _should_ have failed frequently or at least have
>     >     yielded abnormal results often enough to be noticed.  Why wasn't it the case?
>     > 
>     >     I will stop here for the moment.
>     > 
>     > [Ben]
>     > Yes this should be initialized. The reason this got through is that as i defaults to 0 and the 0th bank housed the required data. the case where SRAMS that can be written to, 0xFFE20000 in this case of split mode and on R5-0, was not caught.
>     > 
> 
>     Here @i is a variable allocated on the stack and as such it is garanteed to be
>     garbage on initialisation - it will do anything but default to 0.
> 
> Ok.
> 
>     > Instead of i I will use 
>     > 
>     >                 sram_node = of_parse_phandle(node, BANK_LIST_PROP,              
>     >                                              num_banks - 1); 
> 
>     Do you have to start with the last bank?  If memory serves me well it isn't the
>     case in the previous revisions.  Why not go back to the implementation you had
>     in V25?  
> 
> Makes sense. Will revert as suggested.

For your next revision, go back to V25 and fix only what I commented on.  I
can't remember but you may also have to fix the put_device() problem we've been
discussing. 

> 
>