[media] media: atmel-isi: increase the burst length to improve the performance

The burst length could be BEATS_4/8/16. Before this patch, isi use default
value BEATS_4. To imporve the performance we could set it to BEATS_16.

Otherwise sometime it would cause the ISI overflow error.

Reported-by: Bo Shen <[e-mail]>
Signed-off-by: Josh Wu <[e-mail]>
Signed-off-by: Guennadi Liakhovetski <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

drivers/media/platform/soc_camera/atmel-isi.c

···
 	if (isi->pdata.full_mode)
 		cfg1 |= ISI_CFG1_FULL_MODE;
 
+	cfg1 |= ISI_CFG1_THMASK_BEATS_16;
+
 	isi_writel(isi, ISI_CTRL, ISI_CTRL_DIS);
 	isi_writel(isi, ISI_CFG1, cfg1);
 

include/media/atmel-isi.h

···
 #define		ISI_CFG1_FRATE_DIV_MASK		(7 << 8)
 #define ISI_CFG1_DISCR				(1 << 11)
 #define ISI_CFG1_FULL_MODE			(1 << 12)
+/* Definition for THMASK(ISI_V2) */
+#define		ISI_CFG1_THMASK_BEATS_4		(0 << 13)
+#define		ISI_CFG1_THMASK_BEATS_8		(1 << 13)
+#define		ISI_CFG1_THMASK_BEATS_16	(2 << 13)
 
 /* Bitfields in CFG2 */
 #define ISI_CFG2_GRAYSCALE			(1 << 13)