From: Stefan Richter <stefanr@s5r6.in-berlin.de>
Date: Tue, 21 Jun 2011 13:24:26 +0000 (+0200)
Subject: firewire: ohci: add a comment on PHY reg access serialization
X-Git-Url: http://git.mmlx.us/?a=commitdiff_plain;h=b14c369d87d7fbf120ad21919d34a8f1290290f1;p=linux-edison.git

firewire: ohci: add a comment on PHY reg access serialization

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
---

diff --git a/drivers/firewire/ohci.c b/drivers/firewire/ohci.c
index 3b6f3429fb4..a818dc83469 100644
--- a/drivers/firewire/ohci.c
+++ b/drivers/firewire/ohci.c
@@ -513,6 +513,12 @@ static inline void flush_writes(const struct fw_ohci *ohci)
 	reg_read(ohci, OHCI1394_Version);
 }
 
+/*
+ * Beware!  read_phy_reg(), write_phy_reg(), update_phy_reg(), and
+ * read_paged_phy_reg() require the caller to hold ohci->phy_reg_mutex.
+ * In other words, only use ohci_read_phy_reg() and ohci_update_phy_reg()
+ * directly.  Exceptions are intrinsically serialized contexts like pci_probe.
+ */
 static int read_phy_reg(struct fw_ohci *ohci, int addr)
 {
 	u32 val;