linux-kernel - [PATCH 02/17] soundwire: intel: fix channel number reported by hardware

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Message-Id: <20190806005522.22642-3-pierre-louis.bossart@linux.intel.com>
Date:   Mon,  5 Aug 2019 19:55:07 -0500
From:   Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
To:     alsa-devel@...a-project.org
Cc:     linux-kernel@...r.kernel.org, tiwai@...e.de, broonie@...nel.org,
        vkoul@...nel.org, gregkh@...uxfoundation.org, jank@...ence.com,
        srinivas.kandagatla@...aro.org, Blauciak@...r.kernel.org,
        Slawomir <slawomir.blauciak@...el.com>,
        Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>,
        Sanyog Kale <sanyog.r.kale@...el.com>
Subject: [PATCH 02/17] soundwire: intel: fix channel number reported by hardware

On all released Intel controllers (CNL/CML/ICL), PDI2 reports an
invalid count, force the correct hardware-supported value

This may have to be revisited with platform-specific values if the
hardware changes, but for now this is good enough.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
---
 drivers/soundwire/intel.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/soundwire/intel.c b/drivers/soundwire/intel.c
index a906789c7f78..fe3266bc1d12 100644
--- a/drivers/soundwire/intel.c
+++ b/drivers/soundwire/intel.c
@@ -390,6 +390,16 @@ intel_pdi_get_ch_cap(struct sdw_intel *sdw, unsigned int pdi_num, bool pcm)
 
 	if (pcm) {
 		count = intel_readw(shim, SDW_SHIM_PCMSYCHC(link_id, pdi_num));
+
+		/*
+		 * WORKAROUND: on all existing Intel controllers, pdi
+		 * number 2 reports channel count as 1 even though it
+		 * supports 8 channels. Performing hardcoding for pdi
+		 * number 2.
+		 */
+		if (pdi_num == 2)
+			count = 7;
+
 	} else {
 		count = intel_readw(shim, SDW_SHIM_PDMSCAP(link_id));
 		count = ((count & SDW_SHIM_PDMSCAP_CPSS) >>
-- 
2.20.1