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Subject[PATCH 4/4] parport: daisy: use new parport device model
Date
Modify parport daisy driver to use the new parallel port device model.

Last attempt was '1aec4211204d ("parport: daisy: use new parport device
model")' which failed as daisy was also trying to load the low level
driver and that resulted in a deadlock.

Cc: Michal Kubecek <mkubecek@suse.cz>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
---

Steven, Michal,
Can you please test this series in your test environment and verify that
I am not breaking anything this time.

drivers/parport/daisy.c | 40 +++++++++++++++++++++++++++++++++++++++-
1 file changed, 39 insertions(+), 1 deletion(-)

diff --git a/drivers/parport/daisy.c b/drivers/parport/daisy.c
index 5484a46dafda..95b5c3363582 100644
--- a/drivers/parport/daisy.c
+++ b/drivers/parport/daisy.c
@@ -45,6 +45,7 @@ static struct daisydev {
static DEFINE_SPINLOCK(topology_lock);

static int numdevs;
+static bool daisy_init_done;

/* Forward-declaration of lower-level functions. */
static int mux_present(struct parport *port);
@@ -87,6 +88,24 @@ static struct parport *clone_parport(struct parport *real, int muxport)
return extra;
}

+static int daisy_drv_probe(struct pardevice *par_dev)
+{
+ struct device_driver *drv = par_dev->dev.driver;
+
+ if (strcmp(drv->name, "daisy_drv"))
+ return -ENODEV;
+ if (strcmp(par_dev->name, daisy_dev_name))
+ return -ENODEV;
+
+ return 0;
+}
+
+static struct parport_driver daisy_driver = {
+ .name = "daisy_drv",
+ .probe = daisy_drv_probe,
+ .devmodel = true,
+};
+
/* Discover the IEEE1284.3 topology on a port -- muxes and daisy chains.
* Return value is number of devices actually detected. */
int parport_daisy_init(struct parport *port)
@@ -98,6 +117,23 @@ int parport_daisy_init(struct parport *port)
int i;
int last_try = 0;

+ if (!daisy_init_done) {
+ /*
+ * flag should be marked true first as
+ * parport_register_driver() might try to load the low
+ * level driver which will lead to announcing new ports
+ * and which will again come back here at
+ * parport_daisy_init()
+ */
+ daisy_init_done = true;
+ i = parport_register_driver(&daisy_driver);
+ if (i) {
+ pr_err("daisy registration failed\n");
+ daisy_init_done = false;
+ return i;
+ }
+ }
+
again:
/* Because this is called before any other devices exist,
* we don't have to claim exclusive access. */
@@ -213,10 +249,12 @@ void parport_daisy_fini(struct parport *port)
struct pardevice *parport_open(int devnum, const char *name)
{
struct daisydev *p = topology;
+ struct pardev_cb par_cb;
struct parport *port;
struct pardevice *dev;
int daisy;

+ memset(&par_cb, 0, sizeof(par_cb));
spin_lock(&topology_lock);
while (p && p->devnum != devnum)
p = p->next;
@@ -230,7 +268,7 @@ struct pardevice *parport_open(int devnum, const char *name)
port = parport_get_port(p->port);
spin_unlock(&topology_lock);

- dev = parport_register_device(port, name, NULL, NULL, NULL, 0, NULL);
+ dev = parport_register_dev_model(port, name, &par_cb, devnum);
parport_put_port(port);
if (!dev)
return NULL;
--
2.11.0
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