[PATCH] mmc: renesas_sdhi: Add missing checks for the presence of quirks

[Geert Uytterhoeven <geert+renesas@xxxxxxxxx>]

When running on an system without any quirks (e.g. R-Car V3U), the
kernel crashes with a NULL pointer dereference:

    Unable to handle kernel NULL pointer dereference at virtual address 0000000000000002
    ...
    Hardware name: Renesas Falcon CPU and Breakout boards based on r8a779a0 (DT)
    Workqueue: events_freezable mmc_rescan
    ...
    Call trace:
     renesas_sdhi_internal_dmac_start_dma+0x54/0x12c
     tmio_process_mrq+0x124/0x274

Fix this by adding the missing checks for the validatity of the
priv->quirks pointer.

Fixes: dce2ba8b2ee8cef6 ("mmc: renesas_sdhi: make 'dmac_only_one_rx' a quirk")
Fixes: d4bfa17a655c6de2 ("mmc: renesas_sdhi: make 'fixed_addr_mode' a quirk")
Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
---
 drivers/mmc/host/renesas_sdhi_internal_dmac.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/mmc/host/renesas_sdhi_internal_dmac.c b/drivers/mmc/host/renesas_sdhi_internal_dmac.c
index 6dd5ade3851b2ba8..90048f74e6221add 100644
--- a/drivers/mmc/host/renesas_sdhi_internal_dmac.c
+++ b/drivers/mmc/host/renesas_sdhi_internal_dmac.c
@@ -374,7 +374,7 @@ renesas_sdhi_internal_dmac_start_dma(struct tmio_mmc_host *host,
 	struct scatterlist *sg = host->sg_ptr;
 	u32 dtran_mode = DTRAN_MODE_BUS_WIDTH;
 
-	if (!priv->quirks->fixed_addr_mode)
+	if (!(priv->quirks && priv->quirks->fixed_addr_mode))
 		dtran_mode |= DTRAN_MODE_ADDR_MODE;
 
 	if (!renesas_sdhi_internal_dmac_map(host, data, COOKIE_MAPPED))
@@ -382,7 +382,7 @@ renesas_sdhi_internal_dmac_start_dma(struct tmio_mmc_host *host,
 
 	if (data->flags & MMC_DATA_READ) {
 		dtran_mode |= DTRAN_MODE_CH_NUM_CH1;
-		if (priv->quirks->dma_one_rx_only &&
+		if (priv->quirks && priv->quirks->dma_one_rx_only &&
 		    test_and_set_bit(SDHI_INTERNAL_DMAC_RX_IN_USE, &global_flags))
 			goto force_pio_with_unmap;
 	} else {
-- 
2.25.1