thunderbolt: Retry DROM read once if parsing fails

commit f022ff7bf377ca94367be05de61277934d42ea74 upstream.

Kai-Heng reported that sometimes DROM parsing of ASUS PA27AC Thunderbolt 3
monitor fails. This makes the driver to fail to add the device so only
DisplayPort tunneling is functional.

It is not clear what exactly happens but waiting for 100 ms and retrying
the read seems to work this around so we do that here.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=206493
Reported-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Tested-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Cc: stable@vger.kernel.org
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/thunderbolt/eeprom.c b/drivers/thunderbolt/eeprom.c
index b451a5aa90b5003256a956186d0867ddf04759db..2db6532d392309580b892b689021459a6ab542e0 100644 (file)
--- a/drivers/thunderbolt/eeprom.c
+++ b/drivers/thunderbolt/eeprom.c
@@ -7,6 +7,7 @@
  */
 
 #include <linux/crc32.h>
+#include <linux/delay.h>
 #include <linux/property.h>
 #include <linux/slab.h>
 #include "tb.h"
@@ -389,8 +390,8 @@ static int tb_drom_parse_entries(struct tb_switch *sw)
                struct tb_drom_entry_header *entry = (void *) (sw->drom + pos);
                if (pos + 1 == drom_size || pos + entry->len > drom_size
                                || !entry->len) {
-                       tb_sw_warn(sw, "drom buffer overrun, aborting\n");
-                       return -EIO;
+                       tb_sw_warn(sw, "DROM buffer overrun\n");
+                       return -EILSEQ;
                }
 
                switch (entry->type) {
@@ -526,7 +527,8 @@ int tb_drom_read(struct tb_switch *sw)
        u16 size;
        u32 crc;
        struct tb_drom_header *header;
-       int res;
+       int res, retries = 1;
+
        if (sw->drom)
                return 0;
 
@@ -611,7 +613,17 @@ parse:
                tb_sw_warn(sw, "drom device_rom_revision %#x unknown\n",
                        header->device_rom_revision);
 
-       return tb_drom_parse_entries(sw);
+       res = tb_drom_parse_entries(sw);
+       /* If the DROM parsing fails, wait a moment and retry once */
+       if (res == -EILSEQ && retries--) {
+               tb_sw_warn(sw, "parsing DROM failed, retrying\n");
+               msleep(100);
+               res = tb_drom_read_n(sw, 0, sw->drom, size);
+               if (!res)
+                       goto parse;
+       }
+
+       return res;
 err:
        kfree(sw->drom);
        sw->drom = NULL;