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rockchip: spi: add driver-data and a 'rxonly_manages_fifo' flag 

The SPI controller's documentation (I only had access to the RK3399,
RK3368 and PX30 TRMs) specifies that, when operating in master-mode,
the controller will stop the SCLK to avoid RXFIFO overruns and TXFIFO
underruns.  Looks like my worries that we'd need to support DMA-330
(aka PL330) to make any further progress were unfounded.

This adds a driver-data structure to capture hardware-specific
settings of individual controller instances (after all, we don't know
if all versions are well-behaved) and adds a 'master_manages_fifo'
flag to it.  The first use of said flag is in the optimised
receive-only transfer-handler, which can now request 64Kframe
(i.e. 128KByte) bursts of data on each reprogramming of CTRLR1
(i.e. every time through the loop).

This improves throughput to 46.85MBit/s (a 94.65% bus-utilisation).

Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
This commit is contained in:
Philipp Tomsich 2019-02-03 16:17:32 +01:00
parent 8aa6c921f7
commit 51a644a1b8
1 changed files with 22 additions and 2 deletions
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24
drivers/spi/rk_spi.c
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@ -26,6 +26,11 @@
/* Change to 1 to output registers at the start of each transaction */
#define DEBUG_RK_SPI 0
struct rockchip_spi_params {
/* RXFIFO overruns and TXFIFO underruns stop the master clock */
bool master_manages_fifo;
};
struct rockchip_spi_platdata {
#if CONFIG_IS_ENABLED(OF_PLATDATA)
struct dtd_rockchip_rk3288_spi of_plat;
@ -364,6 +369,15 @@ static inline int rockchip_spi_16bit_reader(struct udevice *dev,
return 0;
}
/*
* If we know that the hardware will manage RXFIFO overruns
* (i.e. stop the SPI clock until there's space in the FIFO),
* we the allow largest possible chunk size that can be
* represented in CTRLR1.
*/
if (data && data->master_manages_fifo)
max_chunk_size = 0x10000;
// rockchip_spi_configure(dev, mode, size)
rkspi_enable_chip(regs, false);
clrsetbits_le32(&regs->ctrlr0,
@ -524,10 +538,16 @@ static const struct dm_spi_ops rockchip_spi_ops = {
*/
};
const struct rockchip_spi_params rk3399_spi_params = {
.master_manages_fifo = true,
};
static const struct udevice_id rockchip_spi_ids[] = {
{ .compatible = "rockchip,rk3288-spi" },
{ .compatible = "rockchip,rk3368-spi" },
{ .compatible = "rockchip,rk3399-spi" },
{ .compatible = "rockchip,rk3368-spi",
.data = (ulong)&rk3399_spi_params },
{ .compatible = "rockchip,rk3399-spi",
.data = (ulong)&rk3399_spi_params },
{ }
};