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Kernel: Add High Speed support to the SDHC driver

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This should not affect boot times on qemu, as that does not use
dynamic transfer delays in its adma code path.
On real hardware this could potentially double the data throughput,
decreasing load times.
This commit is contained in:
Hendiadyoin1 2023-04-08 15:01:19 +02:00 • committed by Sam Atkins
commit 863d0ac260
Notes: sideshowbarker 2024-07-17 10:39:39 +09:00
1 changed files with 9 additions and 2 deletions
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11
Kernel/Storage/SD/SDHostController.cpp
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@ -32,9 +32,11 @@ static void delay(i64 nanoseconds)
}
constexpr u32 max_supported_sdsc_frequency = 25000000;
constexpr u32 max_supported_sdsc_frequency_high_speed = 50000000;
// In "m_registers->host_configuration_0"
// 2.2.11 Host Control 1 Register
constexpr u32 high_speed_enable = 1 << 2;
constexpr u32 dma_select_adma2_32 = 0b10 << 3;
constexpr u32 dma_select_adma2_64 = 0b11 << 3;
@ -221,8 +223,13 @@ ErrorOr<NonnullLockRefPtr<SDMemoryCard>> SDHostController::try_initialize_insert
u64 capacity = static_cast<u64>(block_count) * block_size;
u64 card_capacity_in_blocks = capacity / block_len;
// TODO: Do high speed initialisation, if supported
TRY(sd_clock_frequency_change(max_supported_sdsc_frequency));
if (m_registers->capabilities.high_speed) {
dbgln("SDHC: Enabling High Speed mode");
m_registers->host_configuration_0 = m_registers->host_configuration_0 | high_speed_enable;
TRY(sd_clock_frequency_change(max_supported_sdsc_frequency_high_speed));
} else {
TRY(sd_clock_frequency_change(max_supported_sdsc_frequency));
}
TRY(issue_command(SD::Commands::select_card, rca));
TRY(wait_for_response());