[media] em28xx: adjust period size at runtime

[platform/adaptation/renesas_rcar/renesas_kernel.git] / drivers / media / usb / em28xx / em28xx-audio.c

diff --git a/drivers/media/usb/em28xx/em28xx-audio.c b/drivers/media/usb/em28xx/em28xx-audio.c
index 26cf431..74575e0 100644 (file)
--- a/drivers/media/usb/em28xx/em28xx-audio.c
+++ b/drivers/media/usb/em28xx/em28xx-audio.c
@@ -293,7 +293,12 @@ static int snd_em28xx_capture_open(struct snd_pcm_substream *substream)
                mutex_unlock(&dev->lock);
        }
 
+       /* Dynamically adjust the period size */
        snd_pcm_hw_constraint_integer(runtime, SNDRV_PCM_HW_PARAM_PERIODS);
+       snd_pcm_hw_constraint_minmax(runtime, SNDRV_PCM_HW_PARAM_PERIOD_BYTES,
+                                    dev->adev.period * 95 / 100,
+                                    dev->adev.period * 105 / 100);
+
        dev->adev.capture_pcm_substream = substream;
 
        return 0;
@@ -803,6 +808,9 @@ static int em28xx_audio_urb_init(struct em28xx *dev)
        em28xx_info("Number of URBs: %d, with %d packets and %d size",
                    num_urb, npackets, urb_size);
 
+       /* Estimate the bytes per period */
+       dev->adev.period = urb_size * npackets;
+
        /* Allocate space to store the number of URBs to be used */
 
        dev->adev.transfer_buffer = kcalloc(num_urb,