Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1947498AbbEBTik (ORCPT ); Sat, 2 May 2015 15:38:40 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:46058 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1946208AbbEBTif (ORCPT ); Sat, 2 May 2015 15:38:35 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Chris Wilson , Dmitry Torokhov , Jani Nikula Subject: [PATCH 3.19 158/177] drm/i915: cope with large i2c transfers Date: Sat, 2 May 2015 21:03:00 +0200 Message-Id: <20150502190127.197030391@linuxfoundation.org> X-Mailer: git-send-email 2.3.7 In-Reply-To: <20150502190119.666291882@linuxfoundation.org> References: <20150502190119.666291882@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4381 Lines: 151 3.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Dmitry Torokhov commit 9535c4757b881e06fae72a857485ad57c422b8d2 upstream. The hardware, according to the specs, is limited to 256 byte transfers, and current driver has no protections in case users attempt to do larger transfers. The code will just stomp over status register and mayhem ensues. Let's split larger transfers into digestable chunks. Doing this allows Atmel MXT driver on Pixel 1 function properly (it hasn't since commit 9d8dc3e529a19e427fd379118acd132520935c5d "Input: atmel_mxt_ts - implement T44 message handling" which tries to consume multiple touchscreen/touchpad reports in a single transaction). Reviewed-by: Chris Wilson Signed-off-by: Dmitry Torokhov Signed-off-by: Jani Nikula Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/i915/i915_reg.h | 1 drivers/gpu/drm/i915/intel_i2c.c | 66 +++++++++++++++++++++++++++++++++------ 2 files changed, 57 insertions(+), 10 deletions(-) --- a/drivers/gpu/drm/i915/i915_reg.h +++ b/drivers/gpu/drm/i915/i915_reg.h @@ -1713,6 +1713,7 @@ enum punit_power_well { #define GMBUS_CYCLE_INDEX (2<<25) #define GMBUS_CYCLE_STOP (4<<25) #define GMBUS_BYTE_COUNT_SHIFT 16 +#define GMBUS_BYTE_COUNT_MAX 256U #define GMBUS_SLAVE_INDEX_SHIFT 8 #define GMBUS_SLAVE_ADDR_SHIFT 1 #define GMBUS_SLAVE_READ (1<<0) --- a/drivers/gpu/drm/i915/intel_i2c.c +++ b/drivers/gpu/drm/i915/intel_i2c.c @@ -270,18 +270,17 @@ gmbus_wait_idle(struct drm_i915_private } static int -gmbus_xfer_read(struct drm_i915_private *dev_priv, struct i2c_msg *msg, - u32 gmbus1_index) +gmbus_xfer_read_chunk(struct drm_i915_private *dev_priv, + unsigned short addr, u8 *buf, unsigned int len, + u32 gmbus1_index) { int reg_offset = dev_priv->gpio_mmio_base; - u16 len = msg->len; - u8 *buf = msg->buf; I915_WRITE(GMBUS1 + reg_offset, gmbus1_index | GMBUS_CYCLE_WAIT | (len << GMBUS_BYTE_COUNT_SHIFT) | - (msg->addr << GMBUS_SLAVE_ADDR_SHIFT) | + (addr << GMBUS_SLAVE_ADDR_SHIFT) | GMBUS_SLAVE_READ | GMBUS_SW_RDY); while (len) { int ret; @@ -303,11 +302,35 @@ gmbus_xfer_read(struct drm_i915_private } static int -gmbus_xfer_write(struct drm_i915_private *dev_priv, struct i2c_msg *msg) +gmbus_xfer_read(struct drm_i915_private *dev_priv, struct i2c_msg *msg, + u32 gmbus1_index) { - int reg_offset = dev_priv->gpio_mmio_base; - u16 len = msg->len; u8 *buf = msg->buf; + unsigned int rx_size = msg->len; + unsigned int len; + int ret; + + do { + len = min(rx_size, GMBUS_BYTE_COUNT_MAX); + + ret = gmbus_xfer_read_chunk(dev_priv, msg->addr, + buf, len, gmbus1_index); + if (ret) + return ret; + + rx_size -= len; + buf += len; + } while (rx_size != 0); + + return 0; +} + +static int +gmbus_xfer_write_chunk(struct drm_i915_private *dev_priv, + unsigned short addr, u8 *buf, unsigned int len) +{ + int reg_offset = dev_priv->gpio_mmio_base; + unsigned int chunk_size = len; u32 val, loop; val = loop = 0; @@ -319,8 +342,8 @@ gmbus_xfer_write(struct drm_i915_private I915_WRITE(GMBUS3 + reg_offset, val); I915_WRITE(GMBUS1 + reg_offset, GMBUS_CYCLE_WAIT | - (msg->len << GMBUS_BYTE_COUNT_SHIFT) | - (msg->addr << GMBUS_SLAVE_ADDR_SHIFT) | + (chunk_size << GMBUS_BYTE_COUNT_SHIFT) | + (addr << GMBUS_SLAVE_ADDR_SHIFT) | GMBUS_SLAVE_WRITE | GMBUS_SW_RDY); while (len) { int ret; @@ -337,6 +360,29 @@ gmbus_xfer_write(struct drm_i915_private if (ret) return ret; } + + return 0; +} + +static int +gmbus_xfer_write(struct drm_i915_private *dev_priv, struct i2c_msg *msg) +{ + u8 *buf = msg->buf; + unsigned int tx_size = msg->len; + unsigned int len; + int ret; + + do { + len = min(tx_size, GMBUS_BYTE_COUNT_MAX); + + ret = gmbus_xfer_write_chunk(dev_priv, msg->addr, buf, len); + if (ret) + return ret; + + buf += len; + tx_size -= len; + } while (tx_size != 0); + return 0; } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/