From e16715c135d80aafea867849f938b080d4f4eadb Mon Sep 17 00:00:00 2001 From: Jeffrey Carlyle Date: Wed, 18 May 2016 18:55:13 -0700 Subject: greybus: interface: retry enumeration of UniPro-only modules Greybus modules will sometimes fail to send the mailbox poke and erroneously be enumerated as UniPro-only modules. The root cause for this on the module side is not fully understand, but it seems that this may be due to "the bootrom bug:" a known problem with the bootrom where linkup will occasionally fail because of a race condition. Before the new hotplug code was implemented in the firmware, the SVC would retry enumeration of modules that did not send the mailbox poke; this patch ports that functionality to the AP. Signed-off-by: Jeffrey Carlyle Signed-off-by: Greg Kroah-Hartman --- drivers/staging/greybus/module.c | 21 ++++++++++++++++++++- 1 file changed, 20 insertions(+), 1 deletion(-) (limited to 'drivers/staging/greybus/module.c') diff --git a/drivers/staging/greybus/module.c b/drivers/staging/greybus/module.c index 5077253037c8..ea5895475181 100644 --- a/drivers/staging/greybus/module.c +++ b/drivers/staging/greybus/module.c @@ -138,13 +138,32 @@ static void gb_module_register_interface(struct gb_interface *intf) struct gb_module *module = intf->module; u8 intf_id = intf->interface_id; int ret; + int retries = 3; mutex_lock(&intf->mutex); - ret = gb_interface_activate(intf); + while (retries--) { + ret = gb_interface_activate(intf); + if (ret != -EAGAIN) + break; + } if (ret) { dev_err(&module->dev, "failed to activate interface %u: %d\n", intf_id, ret); + + /* + * -EAGAIN indicates that the Greybus operation + * interface_activate determined the remote interface to be + * UniPro-only. At present, we assume a UniPro-only module + * to be a Greybus module that failed to send its mailbox + * poke. There is some reason to believe that this is + * because of a bug in the ES3 bootrom. If we exhause our + * retries trying to activate such an interface, convert + * the error code back into a "no device" error. + */ + if (ret == -EAGAIN) + ret = -ENODEV; + gb_interface_add(intf); goto err_unlock; } -- cgit v1.2.3