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

From: Ben Levinsky
Date: Sun Mar 21 2021 - 20:20:37 EST

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Hi Mathieu

-----Original Message-----
From: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
Date: Wednesday, March 17, 2021 at 9:27 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 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.

Ok will do. Few things:

Update per minor comments

1.
For SRAM parsing and usage, I would like to check if in v27 the SRAM collection and validation is done from a single function called by zynqmp_r5_probe() for each core with the loop cleaned up to match v25. Then if this SRAM information is only used in parse_fw and prepare/unprepared is ok?

This way in rproc core's parse_fw, the only thing that is occurring is the creation of rproc carveouts. As prepare occurs before parse_fw, the Xilinx-specific initialization occurs before parse_fw anyway.

I am envisioning this as:
1. zynqmp_r5_remoteproc_probe
2. zynqmp_r5_probe
3. zynqmp_r5_tcm_init - collect and validate SRAM information for each core
4. zynqmp_r5_prepare - call Xilinx request_node as initially suggested
5. zynqmp_r5_parse_fw - construct carveouts from DDR and SRAMs
6. zynqmp_r5_rproc_start
7. zynqmp_r5_unprepare - unprepared does the release as initially suggested

2.
For the struct device pointer, in v25 you commented to remove it being stored:

> + /* 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;
> + z_rproc->dev = dev;

Here z_rproc->dev is the same as z_rproc->rproc->dev->parent and as far as I can
tell z_rproc->rproc is available where z_rproc->dev is used. As such
zynqmpq_r5_rproc::dev can likely be removed.

will remove the ptr.

For the management of the device pointer and device tree node how is the following:
zynqmp_r5_remoteproc_probe
...
/* probe each individual r5 core's remoteproc-related info */
for_each_available_child_of_node(dev->of_node, nc) {
child_pdev = of_find_device_by_node(nc);
if (!child_pdev) {
dev_err(dev, "could not get R5 core platform device\n");
ret = -ENODEV;
goto put_node;
}

z_rproc = zynqmp_r5_probe(child_pdev, nc, rpu_mode);
dev_dbg(dev, "%s to probe rpu %pOF\n",
ret ? "Failed" : "Able", nc);
if (IS_ERR(z_rproc)) {
put_device(dev);
ret = PTR_ERR(z_rproc);
goto put_device;
}
list_add_tail(&z_rproc->elem, cluster);
}

put_device:
put_device(dev);
put_node:
of_node_put(nc);
out:
list_for_each(pos, cluster) {
....

Thanks
Ben

>
>

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In reply to: Ben Levinsky: "Re: [PATCH v26 5/5] remoteproc: Add initial zynqmp R5 remoteproc driver"
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