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SubjectRE: [PATCH v15 5/5] remoteproc: Add initial zynqmp R5 remoteproc driver
Date
Hi Michael,

> -----Original Message-----
> From: Michael Auchter <michael.auchter@ni.com>
> Sent: Monday, September 21, 2020 3:12 PM
> To: Ben Levinsky <BLEVINSK@xilinx.com>
> Cc: sunnyliangjy@gmail.com; punit1.agrawal@toshiba.co.jp; Stefano Stabellini
> <stefanos@xilinx.com>; Michal Simek <michals@xilinx.com>;
> devicetree@vger.kernel.org; mathieu.poirier@linaro.org; Ed T. Mooring
> <emooring@xilinx.com>; linux-remoteproc@vger.kernel.org; linux-
> kernel@vger.kernel.org; robh+dt@kernel.org; linux-arm-
> kernel@lists.infradead.org; Jiaying Liang <jliang@xilinx.com>; Michal Simek
> <michals@xilinx.com>; Ed T. Mooring <emooring@xilinx.com>; Jason Wu
> <j.wu@xilinx.com>
> Subject: Re: [PATCH v15 5/5] remoteproc: Add initial zynqmp R5 remoteproc
> driver
>
> Hey Ben,
>
> Thanks for sending out the new series, this patchset is functional for
> booting both R5 0 and R5 1 in split mode.
>
> A few comments below, still working my way through the rest of the code
> though now that this works.
>
> On Mon, Sep 21, 2020 at 09:14:06AM -0700, Ben Levinsky wrote:
> <...>
> > +static int zynqmp_r5_remoteproc_probe(struct platform_device *pdev)
> > +{
> > + int ret, i = 0;
> > + struct device *dev = &pdev->dev;
> > + struct device_node *nc;
> > +
> > + rpu_mode = of_get_property(dev->of_node, "lockstep-mode", NULL)
> ?
> > + PM_RPU_MODE_LOCKSTEP : PM_RPU_MODE_SPLIT;
>
> Extra whitespace, and of_property_read_bool would read a bit nicer here
> (does the same thing in the end, though).
>
> Since rpu_mode is only used here and in r5_set_mode, I think it'd be
> better to plumb it through zynqmp_r5_probe instead of making it global
> in this file.
>
[Ben Levinsky] will do
> > +
> > + dev_dbg(dev, "RPU configuration: %s\n",
> > + rpu_mode == PM_RPU_MODE_LOCKSTEP ? "lockstep" :
> "split");
> > +
> > + for_each_available_child_of_node(dev->of_node, nc) {
> > + /*
> > + * if 2 RPUs provided but one is lockstep, then we have an
> > + * invalid configuration.
> > + */
> > + if (i > 0 && rpu_mode == PM_RPU_MODE_LOCKSTEP)
> > + return -EINVAL;
> > +
> > + /* only call zynqmp_r5_probe if proper # of rpu's */
> > + ret = (i < MAX_RPROCS) ? zynqmp_r5_probe(&rpus[i], pdev,
> nc) :
> > + -EINVAL;
> > + dev_dbg(dev, "%s to probe rpu %pOF\n",
> > + ret ? "Failed" : "Able",
> > + nc);
>
> It'd be cleaner to check the child node count before the loop:
>
> rpu_nodes = of_get_available_child_count(nc)
> if ((rpu_mode == PM_RPU_MODE_LOCKSTEP && rpu_nodes != 1) ||
> rpu_nodes > 2)
> return -EINVAL;
>
[Ben Levinsky] will do
> > +
> > + if (ret)
> > + return ret;
> > +
> > + i++;
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +static int zynqmp_r5_remoteproc_remove(struct platform_device *pdev)
> > +{
> > + int i;
> > +
> > + for (i = 0; i < MAX_RPROCS; i++) {
> > + struct zynqmp_r5_pdata *pdata = &rpus[i];
> > + struct rproc *rproc;
> > +
> > + /* only do clean up for pdata with active rpu */
> > + if (pdata->pnode_id == 0)
> > + continue;
>
> This seems like a bit of a hack, resulting from the use of a static
> array for holding the zynqmp_r5_pdata for each rpu.
>
> Consider allocating zynqmp_r5_pdata in zynqmp_r5_probe, and adding each
> instance to a linked-list at file scope.
> - memory is only allocated RPUs actually in use
> - no need for this pnode_id == 0 hack
> - MAX_RPROCS can be eliminated, just traverse that list in
> remove
> - No reuse of the pdata across probe/removes, so all of the e.g.
> condtionals below ("if (rproc)") and NULL assignments can be
> eliminated.
>
[Ben Levinsky] so parts of this I can do..
- can make the rpus a static list of ptr's which I think is equivalent
To what you are describing
- can eliminate the pnode_id == 0 hack

For the rproc_del, rproc_free fn calls, these should stay. Just as other upstream remoteproc drivers do, this is being done similarly.

For mbox handling, I am mimic'ing upstream ST and TI drivers https://github.com/torvalds/linux/blob/v5.9-rc3/drivers/remoteproc/stm32_rproc.c
they similarly check if the mbox channel is not NULL, and if so call mbox_free_channel. This is similar for Xilinx remoteproc R5 use case as the mbox can be unused in 1 remoteproc node. Also, similar to TI and ST driver, https://github.com/torvalds/linux/blob/v5.9-rc3/drivers/remoteproc/stm32_rproc.c#L321 , I am setting the mbox to NULL at remove
> > +
> > + rproc = pdata->rproc;
> > + if (rproc) {
> > + rproc_del(rproc);
> > + rproc_free(rproc);
> > + pdata->rproc = NULL;
> > + }
> > + if (pdata->tx_chan) {
> > + mbox_free_channel(pdata->tx_chan);
> > + pdata->tx_chan = NULL;
> > + }
> > + if (pdata->rx_chan) {
> > + mbox_free_channel(pdata->rx_chan);
> > + pdata->rx_chan = NULL;
> > + }
> > + if (&(&pdata->dev)->dma_pools)
> > + device_unregister(&pdata->dev);
>
> The condition here looks very wrong to me, as it will always be true.
> What is this trying to achieve?
>
This was originally because of the static rpu declaration. By instead using ptr's this can be removed as the zynqmp_r5_pdata ptr will be NULL so I can check that instead. So will remove this.

Thank you for the review
Ben
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +/* Match table for OF platform binding */
> > +static const struct of_device_id zynqmp_r5_remoteproc_match[] = {
> > + { .compatible = "xlnx,zynqmp-r5-remoteproc-1.0", },
> > + { /* end of list */ },
> > +};
> > +MODULE_DEVICE_TABLE(of, zynqmp_r5_remoteproc_match);
> > +
> > +static struct platform_driver zynqmp_r5_remoteproc_driver = {
> > + .probe = zynqmp_r5_remoteproc_probe,
> > + .remove = zynqmp_r5_remoteproc_remove,
> > + .driver = {
> > + .name = "zynqmp_r5_remoteproc",
> > + .of_match_table = zynqmp_r5_remoteproc_match,
> > + },
> > +};
> > +module_platform_driver(zynqmp_r5_remoteproc_driver);
> > +
> > +MODULE_AUTHOR("Ben Levinsky <ben.levinsky@xilinx.com>");
> > +MODULE_LICENSE("GPL v2");
> > --
> > 2.17.1
> >
>
> Thanks,
> Michael

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