From: jsg <jsg@openbsd.org>
Date: Thu, 14 Dec 2023 05:25:39 +0000 (+0000)
Subject: drm/amdgpu: Remove redundant I2C EEPROM address
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=02860839843f0caf250a2fbbd3e71a8c21e18ffe;p=openbsd

drm/amdgpu: Remove redundant I2C EEPROM address

From Luben Tuikov
ee9efcdc76af0dcb51579aa61c5019eabce93d73 in linux-6.1.y/6.1.68
da858deab88eb561f2196bc99b6dbd2320e56456 in mainline linux
---

diff --git a/sys/dev/pci/drm/amd/amdgpu/amdgpu_eeprom.c b/sys/dev/pci/drm/amd/amdgpu/amdgpu_eeprom.c
index 4ff99326d93..b567d418566 100644
--- a/sys/dev/pci/drm/amd/amdgpu/amdgpu_eeprom.c
+++ b/sys/dev/pci/drm/amd/amdgpu/amdgpu_eeprom.c
@@ -79,6 +79,8 @@
  * That is, for an I2C EEPROM driver everything is controlled by
  * the "eeprom_addr".
  *
+ * See also top of amdgpu_ras_eeprom.c.
+ *
  * P.S. If you need to write, lock and read the Identification Page,
  * (M24M02-DR device only, which we do not use), change the "7" to
  * "0xF" in the macro below, and let the client set bit 20 to 1 in
diff --git a/sys/dev/pci/drm/amd/amdgpu/amdgpu_ras_eeprom.c b/sys/dev/pci/drm/amd/amdgpu/amdgpu_ras_eeprom.c
index 1af25e03ccc..be7ca4f2cd0 100644
--- a/sys/dev/pci/drm/amd/amdgpu/amdgpu_ras_eeprom.c
+++ b/sys/dev/pci/drm/amd/amdgpu/amdgpu_ras_eeprom.c
@@ -33,12 +33,30 @@
 
 #include "amdgpu_reset.h"
 
+/* These are memory addresses as would be seen by one or more EEPROM
+ * chips strung on the I2C bus, usually by manipulating pins 1-3 of a
+ * set of EEPROM devices. They form a continuous memory space.
+ *
+ * The I2C device address includes the device type identifier, 1010b,
+ * which is a reserved value and indicates that this is an I2C EEPROM
+ * device. It also includes the top 3 bits of the 19 bit EEPROM memory
+ * address, namely bits 18, 17, and 16. This makes up the 7 bit
+ * address sent on the I2C bus with bit 0 being the direction bit,
+ * which is not represented here, and sent by the hardware directly.
+ *
+ * For instance,
+ *   50h = 1010000b => device type identifier 1010b, bits 18:16 = 000b, address 0.
+ *   54h = 1010100b => --"--, bits 18:16 = 100b, address 40000h.
+ *   56h = 1010110b => --"--, bits 18:16 = 110b, address 60000h.
+ * Depending on the size of the I2C EEPROM device(s), bits 18:16 may
+ * address memory in a device or a device on the I2C bus, depending on
+ * the status of pins 1-3. See top of amdgpu_eeprom.c.
+ */
 #define EEPROM_I2C_MADDR_VEGA20         0x0
 #define EEPROM_I2C_MADDR_ARCTURUS       0x40000
 #define EEPROM_I2C_MADDR_ARCTURUS_D342  0x0
 #define EEPROM_I2C_MADDR_SIENNA_CICHLID 0x0
 #define EEPROM_I2C_MADDR_ALDEBARAN      0x0
-#define EEPROM_I2C_MADDR_54H            (0x54UL << 16)
 
 /*
  * The 2 macros bellow represent the actual size in bytes that
@@ -134,7 +152,7 @@ static bool __get_eeprom_i2c_addr_ip_discovery(struct amdgpu_device *adev,
 	switch (adev->ip_versions[MP1_HWIP][0]) {
 	case IP_VERSION(13, 0, 0):
 	case IP_VERSION(13, 0, 10):
-		control->i2c_address = EEPROM_I2C_MADDR_54H;
+		control->i2c_address = EEPROM_I2C_MADDR_ARCTURUS;
 		return true;
 	default:
 		return false;
@@ -189,7 +207,7 @@ static bool __get_eeprom_i2c_addr(struct amdgpu_device *adev,
 
 	switch (adev->ip_versions[MP1_HWIP][0]) {
 	case IP_VERSION(13, 0, 0):
-		control->i2c_address = EEPROM_I2C_MADDR_54H;
+		control->i2c_address = EEPROM_I2C_MADDR_ARCTURUS;
 		break;
 
 	default: