This patch brings a lot of fixes to MMIO interface such as:
1. Using 1ms waits instead of 100us.
2. Checking if Timed out before reading and writing
3. Adding missing wait before gmux_mmio_write32

Co-developed-by: Andre Eikmeyer <[email protected]>
Signed-off-by: Andre Eikmeyer <[email protected]>

Signed-off-by: Atharva Tiwari <[email protected]>
---
 drivers/platform/x86/apple-gmux.c | 59 ++++++++++++++++++-------------
 1 file changed, 35 insertions(+), 24 deletions(-)

diff --git a/drivers/platform/x86/apple-gmux.c 
b/drivers/platform/x86/apple-gmux.c
index 4e8786a5e..076ed7ba6 100644
--- a/drivers/platform/x86/apple-gmux.c
+++ b/drivers/platform/x86/apple-gmux.c
@@ -237,8 +237,8 @@ static int gmux_mmio_wait(struct apple_gmux_data *gmux_data)
        u8 gwr = ioread8(gmux_data->iomem_base + GMUX_MMIO_COMMAND_SEND);
 
        while (i && gwr) {
+               fsleep(1000);
                gwr = ioread8(gmux_data->iomem_base + GMUX_MMIO_COMMAND_SEND);
-               udelay(100);
                i--;
        }
 
@@ -250,12 +250,14 @@ static u8 gmux_mmio_read8(struct apple_gmux_data 
*gmux_data, int port)
        u8 val;
 
        mutex_lock(&gmux_data->index_lock);
-       gmux_mmio_wait(gmux_data);
-       iowrite8((port & 0xff), gmux_data->iomem_base + GMUX_MMIO_PORT_SELECT);
-       iowrite8(GMUX_MMIO_READ | sizeof(val),
-               gmux_data->iomem_base + GMUX_MMIO_COMMAND_SEND);
-       gmux_mmio_wait(gmux_data);
-       val = ioread8(gmux_data->iomem_base);
+       if (gmux_mmio_wait(gmux_data)) {
+               iowrite8((port & 0xff), gmux_data->iomem_base + 
GMUX_MMIO_PORT_SELECT);
+               iowrite8(GMUX_MMIO_READ | sizeof(val),
+                       gmux_data->iomem_base + GMUX_MMIO_COMMAND_SEND);
+               if (!gmux_mmio_wait(gmux_data))
+                       return 0;
+               val = ioread8(gmux_data->iomem_base);
+       }
        mutex_unlock(&gmux_data->index_lock);
 
        return val;
@@ -265,14 +267,17 @@ static void gmux_mmio_write8(struct apple_gmux_data 
*gmux_data, int port,
                              u8 val)
 {
        mutex_lock(&gmux_data->index_lock);
-       gmux_mmio_wait(gmux_data);
-       iowrite8(val, gmux_data->iomem_base);
 
-       iowrite8(port & 0xff, gmux_data->iomem_base + GMUX_MMIO_PORT_SELECT);
-       iowrite8(GMUX_MMIO_WRITE | sizeof(val),
-               gmux_data->iomem_base + GMUX_MMIO_COMMAND_SEND);
+       if (gmux_mmio_wait(gmux_data)) {
+               iowrite8(val, gmux_data->iomem_base);
 
-       gmux_mmio_wait(gmux_data);
+               iowrite8(port & 0xff, gmux_data->iomem_base + 
GMUX_MMIO_PORT_SELECT);
+               iowrite8(GMUX_MMIO_WRITE | sizeof(val),
+                       gmux_data->iomem_base + GMUX_MMIO_COMMAND_SEND);
+
+               /* We already wrote the value there is no point to check if 
timeout */
+               gmux_mmio_wait(gmux_data);
+       }
        mutex_unlock(&gmux_data->index_lock);
 }
 
@@ -281,12 +286,16 @@ static u32 gmux_mmio_read32(struct apple_gmux_data 
*gmux_data, int port)
        u32 val;
 
        mutex_lock(&gmux_data->index_lock);
-       gmux_mmio_wait(gmux_data);
-       iowrite8((port & 0xff), gmux_data->iomem_base + GMUX_MMIO_PORT_SELECT);
-       iowrite8(GMUX_MMIO_READ | sizeof(val),
-               gmux_data->iomem_base + GMUX_MMIO_COMMAND_SEND);
-       gmux_mmio_wait(gmux_data);
-       val = ioread32be(gmux_data->iomem_base);
+
+       if (gmux_mmio_wait(gmux_data)) {
+               iowrite8((port & 0xff), gmux_data->iomem_base + 
GMUX_MMIO_PORT_SELECT);
+               iowrite8(GMUX_MMIO_READ | sizeof(val),
+                       gmux_data->iomem_base + GMUX_MMIO_COMMAND_SEND);
+               if (!gmux_mmio_wait(gmux_data))
+                       return 0;
+
+               val = ioread32be(gmux_data->iomem_base);
+       }
        mutex_unlock(&gmux_data->index_lock);
 
        return val;
@@ -296,11 +305,13 @@ static void gmux_mmio_write32(struct apple_gmux_data 
*gmux_data, int port,
                               u32 val)
 {
        mutex_lock(&gmux_data->index_lock);
-       iowrite32be(val, gmux_data->iomem_base);
-       iowrite8(port & 0xff, gmux_data->iomem_base + GMUX_MMIO_PORT_SELECT);
-       iowrite8(GMUX_MMIO_WRITE | sizeof(val),
-               gmux_data->iomem_base + GMUX_MMIO_COMMAND_SEND);
-       gmux_mmio_wait(gmux_data);
+       if (gmux_mmio_wait(gmux_data)) {
+               iowrite32be(val, gmux_data->iomem_base);
+               iowrite8(port & 0xff, gmux_data->iomem_base + 
GMUX_MMIO_PORT_SELECT);
+               iowrite8(GMUX_MMIO_WRITE | sizeof(val),
+                       gmux_data->iomem_base + GMUX_MMIO_COMMAND_SEND);
+               gmux_mmio_wait(gmux_data);
+       }
        mutex_unlock(&gmux_data->index_lock);
 }
 
-- 
2.55.0

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