Commit 0b92e2f4 authored by Philipp Zabel's avatar Philipp Zabel Committed by Greg Kroah-Hartman
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staging: drm/imx: ipu-dmfc: fix bandwidth allocation 



The IPU can request up to four pixels per access, which gives four
times the bandwidth compared to what the driver currently assumes.
After correcting this, we have to increase safety margins for
bandwidth requirement calculations.

Signed-off-by: default avatarPhilipp Zabel <p.zabel@pengutronix.de>
Acked-by: default avatarSascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent ba776c18

drivers/staging/imx-drm/ipu-v3/ipu-dmfc.c

+13 −3
Original line number Diff line number Diff line
@@ -292,7 +292,7 @@ int ipu_dmfc_alloc_bandwidth(struct dmfc_channel *dmfc, 
{

	struct ipu_dmfc_priv *priv = dmfc->priv;

	int slots = dmfc_bandwidth_to_slots(priv, bandwidth_pixel_per_second);

	int segment = 0, ret = 0;

	int segment = -1, ret = 0;



	dev_dbg(priv->dev, "dmfc: trying to allocate %ldMpixel/s for IPU channel %d\n",

			bandwidth_pixel_per_second / 1000000,
@@ -307,6 +307,16 @@ int ipu_dmfc_alloc_bandwidth(struct dmfc_channel *dmfc, 
		goto out;

	}



	/* Always allocate at least 128*4 bytes (2 slots) */

	if (slots < 2)

		slots = 2;



	/* For the MEM_BG channel, first try to allocate twice the slots */

	if (dmfc->data->ipu_channel == IPUV3_CHANNEL_MEM_BG_SYNC)

		segment = dmfc_find_slots(priv, slots * 2);

	if (segment >= 0)

		slots *= 2;

	else

		segment = dmfc_find_slots(priv, slots);

	if (segment < 0) {

		ret = -EBUSY;
@@ -391,7 +401,7 @@ int ipu_dmfc_init(struct ipu_soc *ipu, struct device *dev, unsigned long base, 
	 * We have a total bandwidth of clkrate * 4pixel divided

	 * into 8 slots.

	 */

	priv->bandwidth_per_slot = clk_get_rate(ipu_clk) / 8;

	priv->bandwidth_per_slot = clk_get_rate(ipu_clk) * 4 / 8;



	dev_dbg(dev, "dmfc: 8 slots with %ldMpixel/s bandwidth each\n",

			priv->bandwidth_per_slot / 1000000);

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