[PATCH v1 2/4] staging: fbtft: ssd1351: send gamma table via fbtft_write_buf_dc()

[Sun Jian <sun.jian.kdev@gmail.com>]

Clang reports a large stack frame in set_gamma() (-Wframe-larger-than=1024)
due to the large write_reg() call emitting 63 gamma bytes via varargs.

Send the command byte (0xB8) and the gamma payload using
fbtft_write_buf_dc() to avoid the varargs/NUMARGS stack blow-up.

No functional change intended.

Signed-off-by: Sun Jian <sun.jian.kdev@gmail.com>
---
 drivers/staging/fbtft/fb_ssd1351.c | 35 +++++++++++++-----------------
 1 file changed, 15 insertions(+), 20 deletions(-)

diff --git a/drivers/staging/fbtft/fb_ssd1351.c b/drivers/staging/fbtft/fb_ssd1351.c
index 6736b09b2f45..b4ab2c81e528 100644
--- a/drivers/staging/fbtft/fb_ssd1351.c
+++ b/drivers/staging/fbtft/fb_ssd1351.c
@@ -119,43 +119,38 @@ static int set_var(struct fbtft_par *par)
  */
 static int set_gamma(struct fbtft_par *par, u32 *curves)
 {
-	unsigned long tmp[GAMMA_NUM * GAMMA_LEN];
+	u8 data[GAMMA_LEN];
+	u8 cmd = 0xB8;
 	int i, acc = 0;
+	int ret;
 
-	for (i = 0; i < 63; i++) {
+	for (i = 0; i < GAMMA_LEN; i++) {
 		if (i > 0 && curves[i] < 2) {
 			dev_err(par->info->device,
 				"Illegal value in Grayscale Lookup Table at index %d : %d. Must be greater than 1\n",
 				i, curves[i]);
 			return -EINVAL;
 		}
+
 		acc += curves[i];
-		tmp[i] = acc;
+
 		if (acc > 180) {
 			dev_err(par->info->device,
 				"Illegal value(s) in Grayscale Lookup Table. At index=%d : %d, the accumulated value has exceeded 180\n",
 				i, acc);
 			return -EINVAL;
 		}
+
+		data[i] = acc;
 	}
 
-	write_reg(par, 0xB8,
-		  tmp[0],  tmp[1],  tmp[2],  tmp[3],
-		  tmp[4],  tmp[5],  tmp[6],  tmp[7],
-		  tmp[8],  tmp[9],  tmp[10], tmp[11],
-		  tmp[12], tmp[13], tmp[14], tmp[15],
-		  tmp[16], tmp[17], tmp[18], tmp[19],
-		  tmp[20], tmp[21], tmp[22], tmp[23],
-		  tmp[24], tmp[25], tmp[26], tmp[27],
-		  tmp[28], tmp[29], tmp[30], tmp[31],
-		  tmp[32], tmp[33], tmp[34], tmp[35],
-		  tmp[36], tmp[37], tmp[38], tmp[39],
-		  tmp[40], tmp[41], tmp[42], tmp[43],
-		  tmp[44], tmp[45], tmp[46], tmp[47],
-		  tmp[48], tmp[49], tmp[50], tmp[51],
-		  tmp[52], tmp[53], tmp[54], tmp[55],
-		  tmp[56], tmp[57], tmp[58], tmp[59],
-		  tmp[60], tmp[61], tmp[62]);
+	ret = fbtft_write_buf_dc(par, &cmd, 1, 0);
+	if (ret < 0)
+		return ret;
+
+	ret = fbtft_write_buf_dc(par, data, sizeof(data), 1);
+	if (ret < 0)
+		return ret;
 
 	return 0;
 }
-- 
2.43.0