[PATCH 2/2] drm/i915/gmbus: Add Wa_16025573575 for PTL for bit-bashing

[Ankit Nautiyal]

As per Wa_16025573575 for PTL, set the GPIO masks bit before starting
bit-bashing and maintain value through the bit-bashing sequence.
After bit-bashing sequence is done, clear the GPIO masks bits.

v2:
-Use new helper for display workarounds. (Jani)
-Use a separate if-block for the workaround. (Gustavo)

Signed-off-by: Ankit Nautiyal <ankit.k.nauti...@intel.com>
---
 .../gpu/drm/i915/display/intel_display_wa.c   |  7 ++++
 .../gpu/drm/i915/display/intel_display_wa.h   |  2 ++
 drivers/gpu/drm/i915/display/intel_gmbus.c    | 34 +++++++++++++++++--
 3 files changed, 41 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_display_wa.c 
b/drivers/gpu/drm/i915/display/intel_display_wa.c
index 70ba66fc7e26..6ba58d9efe60 100644
--- a/drivers/gpu/drm/i915/display/intel_display_wa.c
+++ b/drivers/gpu/drm/i915/display/intel_display_wa.c
@@ -40,11 +40,18 @@ void intel_display_wa_apply(struct intel_display *display)
                gen11_display_wa_apply(display);
 }
 
+static bool intel_display_needs_wa_16025573575(struct intel_display *display)
+{
+       return DISPLAY_VER(display) == 30;
+}
+
 bool __intel_display_wa(struct intel_display *display, enum intel_display_wa 
wa)
 {
        switch (wa) {
        case INTEL_DISPLAY_WA_16023588340:
                return intel_display_needs_wa_16023588340(display);
+       case INTEL_DISPLAY_WA_16025573575:
+               return intel_display_needs_wa_16025573575(display);
        default:
                MISSING_CASE(wa);
                break;
diff --git a/drivers/gpu/drm/i915/display/intel_display_wa.h 
b/drivers/gpu/drm/i915/display/intel_display_wa.h
index 853939ebf1ac..db8f3249bd35 100644
--- a/drivers/gpu/drm/i915/display/intel_display_wa.h
+++ b/drivers/gpu/drm/i915/display/intel_display_wa.h
@@ -8,6 +8,7 @@
 
 #include <linux/types.h>
 #include <i915_utils.h>
+#include "intel_display_core.h"
 
 struct intel_display;
 
@@ -24,6 +25,7 @@ bool intel_display_needs_wa_16023588340(struct intel_display 
*display);
 
 enum intel_display_wa {
        INTEL_DISPLAY_WA_16023588340,
+       INTEL_DISPLAY_WA_16025573575,
 };
 
 bool __intel_display_wa(struct intel_display *display, enum intel_display_wa 
wa);
diff --git a/drivers/gpu/drm/i915/display/intel_gmbus.c 
b/drivers/gpu/drm/i915/display/intel_gmbus.c
index 0d73f32fe7f1..95cab11c9cde 100644
--- a/drivers/gpu/drm/i915/display/intel_gmbus.c
+++ b/drivers/gpu/drm/i915/display/intel_gmbus.c
@@ -39,6 +39,7 @@
 #include "intel_de.h"
 #include "intel_display_regs.h"
 #include "intel_display_types.h"
+#include "intel_display_wa.h"
 #include "intel_gmbus.h"
 #include "intel_gmbus_regs.h"
 
@@ -241,11 +242,18 @@ static u32 get_reserved(struct intel_gmbus *bus)
 {
        struct intel_display *display = bus->display;
        u32 reserved = 0;
+       u32 preserve_bits = 0;
 
        /* On most chips, these bits must be preserved in software. */
        if (!display->platform.i830 && !display->platform.i845g)
-               reserved = intel_de_read_notrace(display, bus->gpio_reg) &
-                       (GPIO_DATA_PULLUP_DISABLE | GPIO_CLOCK_PULLUP_DISABLE);
+               preserve_bits |= GPIO_DATA_PULLUP_DISABLE | 
GPIO_CLOCK_PULLUP_DISABLE;
+
+       /* PTL: Wa_16025573575: the masks bits need to be preserved through out 
*/
+       if (intel_display_wa(display, 16025573575))
+               preserve_bits |= GPIO_CLOCK_DIR_MASK | GPIO_CLOCK_VAL_MASK |
+                                GPIO_DATA_DIR_MASK | GPIO_DATA_VAL_MASK;
+
+       reserved = intel_de_read_notrace(display, bus->gpio_reg) & 
preserve_bits;
 
        return reserved;
 }
@@ -308,6 +316,22 @@ static void set_data(void *data, int state_high)
        intel_de_posting_read(display, bus->gpio_reg);
 }
 
+static void
+ptl_handle_mask_bits(struct intel_gmbus *bus, bool set)
+{
+       struct intel_display *display = bus->display;
+       u32 reg_val = intel_de_read_notrace(display, bus->gpio_reg);
+       u32 mask_bits = GPIO_CLOCK_DIR_MASK | GPIO_CLOCK_VAL_MASK |
+                       GPIO_DATA_DIR_MASK | GPIO_DATA_VAL_MASK;
+       if (set)
+               reg_val |= mask_bits;
+       else
+               reg_val &= ~mask_bits;
+
+       intel_de_write_notrace(display, bus->gpio_reg, reg_val);
+       intel_de_posting_read(display, bus->gpio_reg);
+}
+
 static int
 intel_gpio_pre_xfer(struct i2c_adapter *adapter)
 {
@@ -319,6 +343,9 @@ intel_gpio_pre_xfer(struct i2c_adapter *adapter)
        if (display->platform.pineview)
                pnv_gmbus_clock_gating(display, false);
 
+       if (intel_display_wa(display, 16025573575))
+               ptl_handle_mask_bits(bus, true);
+
        set_data(bus, 1);
        set_clock(bus, 1);
        udelay(I2C_RISEFALL_TIME);
@@ -336,6 +363,9 @@ intel_gpio_post_xfer(struct i2c_adapter *adapter)
 
        if (display->platform.pineview)
                pnv_gmbus_clock_gating(display, true);
+
+       if (intel_display_wa(display, 16025573575))
+               ptl_handle_mask_bits(bus, false);
 }
 
 static void
-- 
2.45.2