scsi: ufs: exynos: Fix the maximum segment size

Prepare for enabling DMA clustering and also for supporting PAGE_SIZE !=
4096 by declaring explicitly that the maximum segment size is 4096 bytes
for Exynos UFS host controllers. Add this code in
exynos_ufs_hce_enable_notify() such that it happens after scsi_host_alloc()
and before __scsi_init_queue() is called by the LUN scanning code.

Cc: Alim Akhtar <alim.akhtar@samsung.com>
Cc: Kiwoong Kim <kwmad.kim@samsung.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Alim Akhtar <alim.akhtar@samsung.com>
Tested-by: Alim Akhtar <alim.akhtar@samsung.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/ufs/host/ufs-exynos.c

@@ -1300,6 +1300,14 @@ static int exynos_ufs_hce_enable_notify(struct ufs_hba *hba,
 
 	switch (status) {
 	case PRE_CHANGE:
+		/*
+		 * The maximum segment size must be set after scsi_host_alloc()
+		 * has been called and before LUN scanning starts
+		 * (ufshcd_async_scan()). Note: this callback may also be called
+		 * from other functions than ufshcd_init().
+		 */
+		hba->host->max_segment_size = 4096;
+
 		if (ufs->drv_data->pre_hce_enable) {
 			ret = ufs->drv_data->pre_hce_enable(ufs);
 			if (ret)