linux-kernel - [PATCH v3 2/5] platform/x86: intel_scu_ipc: Replace workaround by 32-bit IO

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Message-ID: <20241021133705.2933464-3-andriy.shevchenko@linux.intel.com>
Date: Mon, 21 Oct 2024 16:34:30 +0300
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Mika Westerberg <mika.westerberg@...ux.intel.com>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	linux-kernel@...r.kernel.org,
	platform-driver-x86@...r.kernel.org
Cc: Andy Shevchenko <andy@...nel.org>,
	Hans de Goede <hdegoede@...hat.com>,
	Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
	Ferry Toth <fntoth@...il.com>
Subject: [PATCH v3 2/5] platform/x86: intel_scu_ipc: Replace workaround by 32-bit IO

The theory is that the so called workaround in pwr_reg_rdwr() is
the actual reader of the data in 32-bit chunks. For some reason
the 8-bit IO won't fail after that. Replace the workaround by using
32-bit IO explicitly and then memcpy() as much data as was requested
by the user. The same approach is already in use in
intel_scu_ipc_dev_command_with_size().

Tested-by: Ferry Toth <fntoth@...il.com>
Acked-by: Mika Westerberg <mika.westerberg@...ux.intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
---
 drivers/platform/x86/intel_scu_ipc.c | 13 +++----------
 1 file changed, 3 insertions(+), 10 deletions(-)

diff --git a/drivers/platform/x86/intel_scu_ipc.c b/drivers/platform/x86/intel_scu_ipc.c
index 8d11d18701a4..290b38627542 100644
--- a/drivers/platform/x86/intel_scu_ipc.c
+++ b/drivers/platform/x86/intel_scu_ipc.c
@@ -217,12 +217,6 @@ static inline u8 ipc_read_status(struct intel_scu_ipc_dev *scu)
 	return __raw_readl(scu->ipc_base + IPC_STATUS);
 }
 
-/* Read ipc byte data */
-static inline u8 ipc_data_readb(struct intel_scu_ipc_dev *scu, u32 offset)
-{
-	return readb(scu->ipc_base + IPC_READ_BUFFER + offset);
-}
-
 /* Read ipc u32 data */
 static inline u32 ipc_data_readl(struct intel_scu_ipc_dev *scu, u32 offset)
 {
@@ -326,10 +320,9 @@ static int pwr_reg_rdwr(struct intel_scu_ipc_dev *scu, u16 *addr, u8 *data,
 
 	err = intel_scu_ipc_check_status(scu);
 	if (!err) { /* Read rbuf */
-		/* Workaround: values are read as 0 without memcpy_fromio */
-		memcpy_fromio(cbuf, scu->ipc_base + 0x90, 16);
-		for (nc = 0; nc < count; nc++)
-			data[nc] = ipc_data_readb(scu, nc);
+		for (nc = 0, offset = 0; nc < 4; nc++, offset += 4)
+			wbuf[nc] = ipc_data_readl(scu, offset);
+		memcpy(data, wbuf, count);
 	}
 	mutex_unlock(&ipclock);
 	return err;
-- 
2.43.0.rc1.1336.g36b5255a03ac