mmc: core: sd: implement proper support for sd3.0 au sizes

This reverts and updates commit 77776fd0a4cc541b9 ("mmc: sd: fix the
maximum au_size for SD3.0"). The au_size for SD3.0 cannot be achieved
by a simple bit shift, so this needs to be implemented differently.
Also, don't print the warning in case of 0 since 'not defined' is
different from 'invalid'.

Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Acked-by: Jaehoon Chung <jh80.chung@samsung.com>
Reviewed-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: stable <stable@vger.kernel.org> # [3.12, 3.13]
Signed-off-by: Chris Ball <chris@printf.net>

1 files changed, 22 insertions, 15 deletions

diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
index 6f42050b7ccc..692fdb177294 100644
--- a/drivers/mmc/core/sd.c
+++ b/drivers/mmc/core/sd.c
@@ -11,6 +11,7 @@
  */
 
 #include <linux/err.h>
+#include <linux/sizes.h>
 #include <linux/slab.h>
 #include <linux/stat.h>
 #include <linux/pm_runtime.h>
@@ -45,6 +46,13 @@ static const unsigned int tacc_mant[] = {
         35,     40,     45,     50,     55,     60,     70,     80,
 };
 
+static const unsigned int sd_au_size[] = {
+        0,              SZ_16K / 512,           SZ_32K / 512,   SZ_64K / 512,
+        SZ_128K / 512,  SZ_256K / 512,          SZ_512K / 512,  SZ_1M / 512,
+        SZ_2M / 512,    SZ_4M / 512,            SZ_8M / 512,    (SZ_8M + SZ_4M) / 512,
+        SZ_16M / 512,   (SZ_16M + SZ_8M) / 512, SZ_32M / 512,   SZ_64M / 512,
+};
+
 #define UNSTUFF_BITS(resp,start,size)                                   \
         ({                                                              \
                 const int __size = size;                                \
@@ -216,7 +224,7 @@ static int mmc_decode_scr(struct mmc_card *card)
 static int mmc_read_ssr(struct mmc_card *card)
 {
         unsigned int au, es, et, eo;
-        int err, i, max_au;
+        int err, i;
         u32 *ssr;
 
         if (!(card->csd.cmdclass & CCC_APP_SPEC)) {
@@ -240,26 +248,25 @@ static int mmc_read_ssr(struct mmc_card *card)
         for (i = 0; i < 16; i++)
                 ssr[i] = be32_to_cpu(ssr[i]);
 
-        /* SD3.0 increases max AU size to 64MB (0xF) from 4MB (0x9) */
-        max_au = card->scr.sda_spec3 ? 0xF : 0x9;
-
         /*
          * UNSTUFF_BITS only works with four u32s so we have to offset the
          * bitfield positions accordingly.
          */
         au = UNSTUFF_BITS(ssr, 428 - 384, 4);
-        if (au > 0 && au <= max_au) {
-                card->ssr.au = 1 << (au + 4);
-                es = UNSTUFF_BITS(ssr, 408 - 384, 16);
-                et = UNSTUFF_BITS(ssr, 402 - 384, 6);
-                eo = UNSTUFF_BITS(ssr, 400 - 384, 2);
-                if (es && et) {
-                        card->ssr.erase_timeout = (et * 1000) / es;
-                        card->ssr.erase_offset = eo * 1000;
+        if (au) {
+                if (au <= 9 || card->scr.sda_spec3) {
+                        card->ssr.au = sd_au_size[au];
+                        es = UNSTUFF_BITS(ssr, 408 - 384, 16);
+                        et = UNSTUFF_BITS(ssr, 402 - 384, 6);
+                        if (es && et) {
+                                eo = UNSTUFF_BITS(ssr, 400 - 384, 2);
+                                card->ssr.erase_timeout = (et * 1000) / es;
+                                card->ssr.erase_offset = eo * 1000;
+                        }
+                } else {
+                        pr_warning("%s: SD Status: Invalid Allocation Unit size.\n",
+                                   mmc_hostname(card->host));
                 }
-        } else {
-                pr_warning("%s: SD Status: Invalid Allocation Unit "
-                        "size.\n", mmc_hostname(card->host));
         }
 out:
         kfree(ssr);