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Date: Thu, 20 Sep 2012 12:24:48 +0200
From: Sjur BRENDELAND <sjur.brandeland@...ricsson.com>
To: Rusty Russell <rusty@...tcorp.com.au>
Cc: Sjur Brændeland <sjurbren@...il.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Linus Walleij <linus.walleij@...aro.org>,
"virtualization@...ts.linux-foundation.org"
<virtualization@...ts.linux-foundation.org>,
"Michael S. Tsirkin" <mst@...hat.com>,
Amit Shah <amit.shah@...hat.com>,
Ohad Ben-Cohen <ohad@...ery.com>
Subject: RE: [PATCHv2] virtio_console: Add support for remoteproc serial
Hi Rusty,
> > +#if IS_ENABLED(CONFIG_REMOTEPROC)
> > +static inline bool is_rproc_serial(struct virtio_device *vdev)
> > +{
> > + return vdev->id.device == VIRTIO_ID_RPROC_SERIAL;
> > +}
> > +#else
> > +static inline bool is_rproc_serial(struct virtio_device *vdev)
> > +{
> > + return false;
> > +}
> > +#endif
>
> I prefer to avoid inline in C files. The compiler knows, and with
> inline you get no warning if it becomes unused. Also, const struct
> virtio_device *.
Sure, I'll fix this.
> > +/* Allocate data buffer from DMA memory if requested */
> > +static inline void *
> > +alloc_databuf(struct virtio_device *vdev, size_t size, gfp_t flag)
> > +{
> > + if (is_rproc_serial(vdev)) {
> > + dma_addr_t dma;
> > + struct device *dev = &vdev->dev;
> > + /*
> > + * Allocate DMA memory from ancestors. Finding the ancestor
> > + * is a bit quirky when DMA_MEMORY_INCLUDES_CHILDREN is not
> > + * implemented.
> > + */
> > + dev = dev->parent ? dev->parent : dev;
> > + dev = dev->parent ? dev->parent : dev;
> > + return dma_alloc_coherent(dev, size, &dma, flag);
>
> Wow, up 2 levels? Why 2? What's special about the grandparents?
In remoteproc we have the following hierarchy:
Virtio Device -> Remoteproc Device -> Platform Device
The DMA memory is associated with the Platform Device.
In my case the platform device does dma_declare_coherent_memory()
before registering to the rproc framework. And I need to call
dma_alloc_coherent with the same device reference that originally
did declare the dma memory.
virtio_rpmsg_bus.c does the same thing. When allocating dma
memory is access the parent: dma_alloc_coherent(vdev->dev.parent->parent,...).
As mentioned in the comment, dma-coherent.c does unfortunately
not implement search for devices parent devices with DMA memory
even if the flag DMA_MEMORY_INCLUDES_CHILDREN is set. If this
feature was in place I could have dropped the genealogy research
I have implemented.
> > -static void free_buf(struct port_buffer *buf)
> > +static void
> > +free_buf(struct virtqueue *vq, struct port_buffer *buf, size_t
> buf_size)
> > {
>
> Generally prefer to indent buf and buf_size, rather than break at
> free_buf.
Ok, I'll fix this.
>
> > + buf = alloc_databuf(vdev, buf_size, GFP_KERNEL);
> >
> > - buf = kmalloc(count, GFP_KERNEL);
> > if (!buf)
> > return -ENOMEM;
>
> This effectively adds a blank line between "buf = ..." and "if (!buf)",
> but they're adjacent because they're logically grouped.
Agree, thanks.
>
> > @@ -767,6 +826,7 @@ static int port_fops_release(struct inode *inode,
> struct file *filp)
> > spin_unlock_irq(&port->inbuf_lock);
> >
> > spin_lock_irq(&port->outvq_lock);
> > +
> > reclaim_consumed_buffers(port);
> > spin_unlock_irq(&port->outvq_lock);
> >
>
> Weird whitespace addition. I know you're doing that simply to check if
> I'm reading, right?
Of course not - it's just me being space out.
> > @@ -1688,7 +1768,7 @@ static void remove_controlq_data(struct
> ports_device *portdev)
> > * config space to see how many ports the host has spawned. We
> > * initialize each port found.
> > */
> > -static int __devinit virtcons_probe(struct virtio_device *vdev)
> > +static int virtcons_probe(struct virtio_device *vdev)
> > {
> > struct ports_device *portdev;
> > int err;
>
> Not sure about this change. If you actually turn off CONFIG_HOTPLUG,
> I wouldn't think that remoteproc would work at all any more, since it
> needs the driver core to match up devices?
Hm, when adding __devinit I get a section mismatch warning in virtio_rproc_serial.
But I guess this is a false positive? I could silence this warning by annotating
virtio_rproc_serial with __refdata.
> > @@ -1724,10 +1804,12 @@ static int __devinit virtcons_probe(struct
> virtio_device *vdev)
> >
> > multiport = false;
> > portdev->config.max_nr_ports = 1;
> > - if (virtio_config_val(vdev, VIRTIO_CONSOLE_F_MULTIPORT,
> > - offsetof(struct virtio_console_config,
> > - max_nr_ports),
> > - &portdev->config.max_nr_ports) == 0)
> > + if (is_rproc_serial(vdev))
> > + multiport = false;
> > + else if (virtio_config_val(vdev, VIRTIO_CONSOLE_F_MULTIPORT,
> > + offsetof(struct virtio_console_config,
> > + max_nr_ports),
> > + &portdev->config.max_nr_ports) == 0)
> > multiport = true;
>
> This is a bit weird, to double-assign multiport = false; it looks
> tacked
> on.
>
> How about:
>
> /* Don't test MULTIPORT at all if we're rproc: not a valid
> feature! */
> if (!is_rproc_serial(vdev)
> && virtio_config_val(vdev, VIRTIO_CONSOLE_F_MULTIPORT,
> offsetof(struct virtio_console_config,
> max_nr_ports),
> &portdev->config.max_nr_ports) == 0) {
> multiport = true;
> } else {
> multiport = false;
> portdev->config.max_nr_ports = 1;
> }
Yes thanks, this looks much better.
>
> > err = init_vqs(portdev);
> > @@ -1838,6 +1920,16 @@ static unsigned int features[] = {
> > VIRTIO_CONSOLE_F_MULTIPORT,
> > };
> >
> > +static struct virtio_device_id rproc_serial_id_table[] = {
> > +#if IS_ENABLED(CONFIG_REMOTEPROC)
> > + { VIRTIO_ID_RPROC_SERIAL, VIRTIO_DEV_ANY_ID },
> > +#endif
> > + { 0 },
> > +};
> > +
> > +static unsigned int rproc_serial_features[] = {
> > +};
> > +
> > #ifdef CONFIG_PM
> > static int virtcons_freeze(struct virtio_device *vdev)
> > {
> > @@ -1922,6 +2014,16 @@ static struct virtio_driver virtio_console = {
> > #endif
> > };
> >
> > +static struct virtio_driver virtio_rproc_serial = {
> > + .feature_table = rproc_serial_features,
> > + .feature_table_size = ARRAY_SIZE(rproc_serial_features),
> > + .driver.name = "virtio_rproc_serial",
> > + .driver.owner = THIS_MODULE,
> > + .id_table = rproc_serial_id_table,
> > + .probe = virtcons_probe,
> > + .remove = virtcons_remove,
> > +};
> > +
> > static int __init init(void)
> > {
> > int err;
> > @@ -1941,12 +2043,16 @@ static int __init init(void)
> > INIT_LIST_HEAD(&pdrvdata.consoles);
> > INIT_LIST_HEAD(&pdrvdata.portdevs);
> >
> > - return register_virtio_driver(&virtio_console);
> > + err = register_virtio_driver(&virtio_console);
> > + if (err)
> > + return err;
> > + return register_virtio_driver(&virtio_rproc_serial);
>
> Hmm, we need to cleanup if the second register fails.
Indeed, I'll add this.
>
> > #define VIRTIO_ID_RPMSG 7 /* virtio remote processor
> messaging */
> > #define VIRTIO_ID_SCSI 8 /* virtio scsi */
> > #define VIRTIO_ID_9P 9 /* 9p virtio console */
> > +#define VIRTIO_ID_RPROC_SERIAL 0xB /* virtio remoteproc serial link
> */
>
> Prefer decimal here...
Sure,
Thank you for reviewing, I send out a new respin of this patch soon.
Regards,
Sjur
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