ASoC: SOF: ipc: retain DSP context after FW exception.

Add config option to prevent DSP entering D3 after any FW exception.
This can then be used to dump FW context for debug.
Signed-off-by: Liam Girdwood <liam.r.girdwood@linux.intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20190927200538.660-5-pierre-louis.bossart@linux.intel.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/sof/Kconfig

@@ -158,6 +158,14 @@ config SND_SOC_SOF_DEBUG_IPC_FLOOD_TEST
 	  Say Y if you want to enable IPC flood test.
 	  If unsure, select "N".
 
+config SND_SOC_SOF_DEBUG_RETAIN_DSP_CONTEXT
+	bool "SOF retain DSP context on any FW exceptions"
+	help
+	  This option keeps the DSP in D0 state so that firmware debug
+	  information can be retained and dumped to userspace.
+	  Say Y if you want to retain DSP context for FW exceptions.
+	  If unsure, select "N".
+
 endif ## SND_SOC_SOF_DEBUG
 
 endif ## SND_SOC_SOF_OPTIONS

sound/soc/sof/debug.c

@@ -461,3 +461,19 @@ void snd_sof_free_debug(struct snd_sof_dev *sdev)
 	debugfs_remove_recursive(sdev->debugfs_root);
 }
 EXPORT_SYMBOL_GPL(snd_sof_free_debug);
+
+void snd_sof_handle_fw_exception(struct snd_sof_dev *sdev)
+{
+	if (IS_ENABLED(CONFIG_SND_SOC_SOF_DEBUG_RETAIN_DSP_CONTEXT) ||
+	    (sof_core_debug & SOF_DBG_RETAIN_CTX)) {
+		/* should we prevent DSP entering D3 ? */
+		dev_info(sdev->dev, "info: preventing DSP entering D3 state to preserve context\n");
+		pm_runtime_get_noresume(sdev->dev);
+	}
+
+	/* dump vital information to the logs */
+	snd_sof_dsp_dbg_dump(sdev, SOF_DBG_REGS | SOF_DBG_MBOX);
+	snd_sof_ipc_dump(sdev);
+	snd_sof_trace_notify_for_error(sdev);
+}
+EXPORT_SYMBOL(snd_sof_handle_fw_exception);

sound/soc/sof/ipc.c

@@ -210,9 +210,7 @@ static int tx_wait_done(struct snd_sof_ipc *ipc, struct snd_sof_ipc_msg *msg,
 	if (ret == 0) {
 		dev_err(sdev->dev, "error: ipc timed out for 0x%x size %d\n",
 			hdr->cmd, hdr->size);
-		snd_sof_dsp_dbg_dump(ipc->sdev, SOF_DBG_REGS | SOF_DBG_MBOX);
-		snd_sof_ipc_dump(ipc->sdev);
-		snd_sof_trace_notify_for_error(ipc->sdev);
+		snd_sof_handle_fw_exception(ipc->sdev);
 		ret = -ETIMEDOUT;
 	} else {
 		/* copy the data returned from DSP */

sound/soc/sof/sof-priv.h

@@ -33,6 +33,7 @@
 #define SOF_DBG_MBOX		BIT(2)
 #define SOF_DBG_TEXT		BIT(3)
 #define SOF_DBG_PCI		BIT(4)
+#define SOF_DBG_RETAIN_CTX	BIT(5)	/* prevent DSP D3 on FW exception */
 
 /* global debug state set by SOF_DBG_ flags */
 extern int sof_core_debug;
@@ -580,6 +581,7 @@ void snd_sof_get_status(struct snd_sof_dev *sdev, u32 panic_code,
 			struct sof_ipc_panic_info *panic_info,
 			void *stack, size_t stack_words);
 int snd_sof_init_trace_ipc(struct snd_sof_dev *sdev);
+void snd_sof_handle_fw_exception(struct snd_sof_dev *sdev);
 
 /*
  * Platform specific ops.