linux/drivers/gpu/drm/amd/display/dc/gpio/gpio_service.h
Yogesh Mohan Marimuthu 50f9ca048c drm/amd/display: fix sporadic multiple aux transaction failure
[why]
When there are multiple aux transaction in parallel, it is sometime
sporadically the aux transaction starts to continuously fail. The
aux transaction was failing because the busy bit for the given gpio
pin was always set. The busy bit was alway set because the
programming sequence to read, modify and write busy bit was not
atomic. Due to which when multiple threads are trying to modify the
busy bits for their gpio pins in the same integer variable sometimes
the busy bits integer variable is written with old data causing
failure.

[how]
Instead of using individual bits to track gpio pins and grouping
them to integers, one byte will be allcoated for each gpio pin.
Now whenever a gpio pin needs to be set to mark being used, only
writing a value of one to that byte is sufficient, other bytes
are not impacted. Also no need to have atomicity with bytes unlike
with bits.

Signed-off-by: Yogesh Mohan Marimuthu <yogesh.mohanmarimuthu@amd.com>
Reviewed-by: Harry Wentland <Harry.Wentland@amd.com>
Acked-by: Leo Li <sunpeng.li@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
2018-11-30 12:01:42 -05:00

56 lines
1.7 KiB
C

/*
* Copyright 2012-15 Advanced Micro Devices, Inc.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*
* Authors: AMD
*
*/
#ifndef __DAL_GPIO_SERVICE_H__
#define __DAL_GPIO_SERVICE_H__
struct hw_translate;
struct hw_factory;
struct gpio_service {
struct dc_context *ctx;
struct hw_translate translate;
struct hw_factory factory;
/*
* @brief
* Business storage.
* one byte For each member of 'enum gpio_id'
*/
char *busyness[GPIO_ID_COUNT];
};
enum gpio_result dal_gpio_service_open(
struct gpio_service *service,
enum gpio_id id,
uint32_t en,
enum gpio_mode mode,
struct hw_gpio_pin **ptr);
void dal_gpio_service_close(
struct gpio_service *service,
struct hw_gpio_pin **ptr);
#endif