mmc: cavium: Set the correct dma max segment size for mmc_host

commit fa25eba6 upstream.

We have set the mmc_host.max_seg_size to 8M, but the dma max segment
size of PCI device is set to 64K by default in function pci_device_add().
The mmc_host.max_seg_size is used to set the max segment size of
the blk queue. Then this mismatch will trigger a calltrace like below
when a bigger than 64K segment request arrives at mmc dev. So we should
consider the limitation of the cvm_mmc_host when setting the
mmc_host.max_seg_size.
  DMA-API: thunderx_mmc 0000:01:01.4: mapping sg segment longer than device claims to support [len=131072] [max=65536]
  WARNING: CPU: 6 PID: 238 at kernel/dma/debug.c:1221 debug_dma_map_sg+0x2b8/0x350
  Modules linked in:
  CPU: 6 PID: 238 Comm: kworker/6:1H Not tainted 5.3.0-rc1-next-20190724-yocto-standard+ #62
  Hardware name: Marvell OcteonTX CN96XX board (DT)
  Workqueue: kblockd blk_mq_run_work_fn
  pstate: 80c00009 (Nzcv daif +PAN +UAO)
  pc : debug_dma_map_sg+0x2b8/0x350
  lr : debug_dma_map_sg+0x2b8/0x350
  sp : ffff00001770f9e0
  x29: ffff00001770f9e0 x28: ffffffff00000000
  x27: 00000000ffffffff x26: ffff800bc2c73180
  x25: ffff000010e83700 x24: 0000000000000002
  x23: 0000000000000001 x22: 0000000000000001
  x21: 0000000000000000 x20: ffff800bc48ba0b0
  x19: ffff800bc97e8c00 x18: ffffffffffffffff
  x17: 0000000000000000 x16: 0000000000000000
  x15: ffff000010e835c8 x14: 6874207265676e6f
  x13: 6c20746e656d6765 x12: 7320677320676e69
  x11: 7070616d203a342e x10: 31303a31303a3030
  x9 : 303020636d6d5f78 x8 : 35363d78616d5b20
  x7 : 00000000000002fd x6 : ffff000010fd57dc
  x5 : 0000000000000000 x4 : ffff0000106c61f0
  x3 : 00000000ffffffff x2 : 0000800bee060000
  x1 : 7010678df3041a00 x0 : 0000000000000000
  Call trace:
   debug_dma_map_sg+0x2b8/0x350
   cvm_mmc_request+0x3c4/0x988
   __mmc_start_request+0x9c/0x1f8
   mmc_start_request+0x7c/0xb0
   mmc_blk_mq_issue_rq+0x5c4/0x7b8
   mmc_mq_queue_rq+0x11c/0x278
   blk_mq_dispatch_rq_list+0xb0/0x568
   blk_mq_do_dispatch_sched+0x6c/0x108
   blk_mq_sched_dispatch_requests+0x110/0x1b8
   __blk_mq_run_hw_queue+0xb0/0x118
   blk_mq_run_work_fn+0x28/0x38
   process_one_work+0x210/0x490
   worker_thread+0x48/0x458
   kthread+0x130/0x138
   ret_from_fork+0x10/0x1c
Signed-off-by: Kevin Hao <haokexin@gmail.com>
Fixes: ba3869ff ("mmc: cavium: Add core MMC driver for Cavium SOCs")
Cc: stable@vger.kernel.org
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/mmc/host/cavium.c

@@ -1046,7 +1046,8 @@ int cvm_mmc_of_slot_probe(struct device *dev, struct cvm_mmc_host *host)
 		mmc->max_segs = 1;
 
 	/* DMA size field can address up to 8 MB */
-	mmc->max_seg_size = 8 * 1024 * 1024;
+	mmc->max_seg_size = min_t(unsigned int, 8 * 1024 * 1024,
+				  dma_get_max_seg_size(host->dev));
 	mmc->max_req_size = mmc->max_seg_size;
 	/* External DMA is in 512 byte blocks */
 	mmc->max_blk_size = 512;