hw/sd: sdhci: Limit block size only when SDHC_BLKSIZE register is writable

The codes to limit the maximum block size is only necessary when
SDHC_BLKSIZE register is writable.

Tested-by: Alexander Bulekov <alxndr@bu.edu>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Message-Id: <20210303122639.20004-5-bmeng.cn@gmail.com>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>

hw/sd/sdhci.c

@@ -1142,15 +1142,15 @@ sdhci_write(void *opaque, hwaddr offset, uint64_t val, unsigned size)
         if (!TRANSFERRING_DATA(s->prnsts)) {
             MASKED_WRITE(s->blksize, mask, extract32(value, 0, 12));
             MASKED_WRITE(s->blkcnt, mask >> 16, value >> 16);
-        }
 
-        /* Limit block size to the maximum buffer size */
-        if (extract32(s->blksize, 0, 12) > s->buf_maxsz) {
-            qemu_log_mask(LOG_GUEST_ERROR, "%s: Size 0x%x is larger than "
-                          "the maximum buffer 0x%x\n", __func__, s->blksize,
-                          s->buf_maxsz);
+            /* Limit block size to the maximum buffer size */
+            if (extract32(s->blksize, 0, 12) > s->buf_maxsz) {
+                qemu_log_mask(LOG_GUEST_ERROR, "%s: Size 0x%x is larger than "
+                              "the maximum buffer 0x%x\n", __func__, s->blksize,
+                              s->buf_maxsz);
 
-            s->blksize = deposit32(s->blksize, 0, 12, s->buf_maxsz);
+                s->blksize = deposit32(s->blksize, 0, 12, s->buf_maxsz);
+            }
         }
 
         break;