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Sat, 24 Oct 2026 21:02:06 -0700 (PDT) Received: from at-Standard-PC-Q35-ICH9-2009 ([106.221.76.40]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-198a32ff780sm11635283c88.22.2026.10.24.21.01.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 24 Oct 2026 21:02:06 -0700 (PDT) From: Atharva Tiwari To: Cc: Atharva Tiwari , Andre Eikmeyer , Bjorn Helgaas , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org (maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)), "H. Peter Anvin" , Alex Deucher , =?UTF-8?q?Christian=20K=C3=B6nig?= , David Airlie , Simona Vetter , Harry Wentland , Leo Li , Rodrigo Siqueira , Kenneth Feng , Hans de Goede , =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= , linux-pci@vger.kernel.org (open list:PCI SUBSYSTEM), linux-kernel@vger.kernel.org (open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)), amd-gfx@lists.freedesktop.org (open list:RADEON and AMDGPU DRM DRIVERS), dri-devel@lists.freedesktop.org (open list:DRM DRIVERS), platform-driver-x86@vger.kernel.org (open list:X86 PLATFORM DRIVERS) Subject: [PATCH 03/13] platform/apple-gmux: Fix MMIO interface Date: Sat, 24 Oct 2026 23:59:39 -0400 Message-ID: <20261025040046.1602-4-atharvatiwarilinuxdev@gmail.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20261025040046.1602-1-atharvatiwarilinuxdev@gmail.com> References: <20261025040046.1602-1-atharvatiwarilinuxdev@gmail.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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 Signed-off-by: Andre Eikmeyer Signed-off-by: Atharva Tiwari --- 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