1 files changed, 40 insertions, 29 deletions

diff --git a/drivers/mtd/devices/m25p80.c b/drivers/mtd/devices/m25p80.c
index 47486fbd7777..e6892851e813 100644
--- a/drivers/mtd/devices/m25p80.c
+++ b/drivers/mtd/devices/m25p80.c
@@ -709,6 +709,14 @@ static const struct spi_device_id *__devinit jedec_probe(struct spi_device *spi)
         jedec = jedec << 8;
         jedec |= id[2];
 
+        /*
+         * Some chips (like Numonyx M25P80) have JEDEC and non-JEDEC variants,
+         * which depend on technology process. Officially RDID command doesn't
+         * exist for non-JEDEC chips, but for compatibility they return ID 0.
+         */
+        if (jedec == 0)
+                return NULL;
+
         ext_jedec = id[3] << 8 | id[4];
 
         for (tmp = 0; tmp < ARRAY_SIZE(m25p_ids) - 1; tmp++) {
@@ -730,7 +738,7 @@ static const struct spi_device_id *__devinit jedec_probe(struct spi_device *spi)
  */
 static int __devinit m25p_probe(struct spi_device *spi)
 {
-        const struct spi_device_id      *id;
+        const struct spi_device_id      *id = spi_get_device_id(spi);
         struct flash_platform_data      *data;
         struct m25p                     *flash;
         struct flash_info               *info;
@@ -743,41 +751,44 @@ static int __devinit m25p_probe(struct spi_device *spi)
          */
         data = spi->dev.platform_data;
         if (data && data->type) {
+                const struct spi_device_id *plat_id;
+
                 for (i = 0; i < ARRAY_SIZE(m25p_ids) - 1; i++) {
-                        id = &m25p_ids[i];
-                        info = (void *)m25p_ids[i].driver_data;
-                        if (strcmp(data->type, id->name))
+                        plat_id = &m25p_ids[i];
+                        if (strcmp(data->type, plat_id->name))
                                 continue;
                         break;
                 }
 
-                /* unrecognized chip? */
-                if (i == ARRAY_SIZE(m25p_ids) - 1) {
-                        DEBUG(MTD_DEBUG_LEVEL0, "%s: unrecognized id %s\n",
-                                        dev_name(&spi->dev), data->type);
-                        info = NULL;
-
-                /* recognized; is that chip really what's there? */
-                } else if (info->jedec_id) {
-                        id = jedec_probe(spi);
-
-                        if (id != &m25p_ids[i]) {
-                                dev_warn(&spi->dev, "found %s, expected %s\n",
-                                                id ? id->name : "UNKNOWN",
-                                                m25p_ids[i].name);
-                                info = NULL;
-                        }
-                }
-        } else {
-                id = jedec_probe(spi);
-                if (!id)
-                        id = spi_get_device_id(spi);
-
-                info = (void *)id->driver_data;
+                if (plat_id)
+                        id = plat_id;
+                else
+                        dev_warn(&spi->dev, "unrecognized id %s\n", data->type);
         }
 
-        if (!info)
-                return -ENODEV;
+        info = (void *)id->driver_data;
+
+        if (info->jedec_id) {
+                const struct spi_device_id *jid;
+
+                jid = jedec_probe(spi);
+                if (!jid) {
+                        dev_info(&spi->dev, "non-JEDEC variant of %s\n",
+                                 id->name);
+                } else if (jid != id) {
+                        /*
+                         * JEDEC knows better, so overwrite platform ID. We
+                         * can't trust partitions any longer, but we'll let
+                         * mtd apply them anyway, since some partitions may be
+                         * marked read-only, and we don't want to lose that
+                         * information, even if it's not 100% accurate.
+                         */
+                        dev_warn(&spi->dev, "found %s, expected %s\n",
+                                 jid->name, id->name);
+                        id = jid;
+                        info = (void *)jid->driver_data;
+                }
+        }
 
         flash = kzalloc(sizeof *flash, GFP_KERNEL);
         if (!flash)