linux-kernel - [PATCH 5.4 016/203] ASoC: SOF: imx8: Fix dsp

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Message-Id: <20200116231746.164130836@linuxfoundation.org>
Date:   Fri, 17 Jan 2020 00:15:33 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Daniel Baluta <daniel.baluta@....com>,
        Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>,
        Mark Brown <broonie@...nel.org>
Subject: [PATCH 5.4 016/203] ASoC: SOF: imx8: Fix dsp_box offset

From: Daniel Baluta <daniel.baluta@....com>

commit dcf08d0f8f09081b16f69071dd55d51d5e964e84 upstream.

dsp_box is used to keep DSP initiated messages. The value of dsp_offset
is set by the DSP with the first message, so we need a way to bootstrap
it in order to get the first message.

We do this by setting the correct default dsp_box offset which on i.MX8
is not zero.

Very interesting is why it has worked until now.

On i.MX8, DSP communicates with ARM core using a shared SDRAM memory
area. Actually, there are two shared areas:
	* SDRAM0 - starting at 0x92400000, size 0x800000
	* SDRAM1 - starting at 0x92C00000, size 0x800000

SDRAM0 keeps the data sections, starting with .rodata. By chance
fw_ready structure was placed at the beginning of .rodata.

dsp_box_base is defined as SDRAM0 + dsp_box_offset and it is placed
at the beginning of SDRAM1 (dsp_box_offset should be 0x800000). But
because it is zero initialized by default it points to SDRAM0 where
by chance the fw_ready was placed in the SOF firmware.

Anyhow, SOF commit 7466bee378dd811b ("clk: make freq arrays constant")
fw_ready is no longer at the beginning of SDRAM0 and everything shows
how lucky we were until now.

Fix this by properly setting the default dsp_box offset.

Fixes: 202acc565a1f050 ("ASoC: SOF: imx: Add i.MX8 HW support")
Signed-off-by: Daniel Baluta <daniel.baluta@....com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
Link: https://lore.kernel.org/r/20191220170531.10423-1-pierre-louis.bossart@linux.intel.com
Signed-off-by: Mark Brown <broonie@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 sound/soc/sof/imx/imx8.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/sound/soc/sof/imx/imx8.c
+++ b/sound/soc/sof/imx/imx8.c
@@ -304,6 +304,9 @@ static int imx8_probe(struct snd_sof_dev
 	}
 	sdev->mailbox_bar = SOF_FW_BLK_TYPE_SRAM;

+	/* set default mailbox offset for FW ready message */
+	sdev->dsp_box.offset = MBOX_OFFSET;
+
 	return 0;

 exit_pdev_unregister: