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Commit 8efd1e9e authored by Chew, Chiau Ee's avatar Chew, Chiau Ee Committed by Wolfram Sang
Browse files

i2c: designware-pci: set ideal HCNT, LCNT and SDA hold time value 



On Intel BayTrail, there was case whereby the resulting fast mode
bus speed becomes slower (~20% slower compared to expected speed)
if using the HCNT/LCNT calculated in the core layer. Thus, this
patch is added to allow pci glue layer to pass in optimal
HCNT/LCNT/SDA hold time values to core layer since the core
layer supports cofigurable HCNT/LCNT/SDA hold time values now.

Signed-off-by: default avatarChew, Chiau Ee <chiau.ee.chew@intel.com>
Acked-by: default avatarMika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: default avatarWolfram Sang <wsa@the-dreams.de>
parent 4fda9962

drivers/i2c/busses/i2c-designware-pcidrv.c

+28 −0
Original line number Diff line number Diff line
@@ -58,6 +58,14 @@ enum dw_pci_ctl_id_t { 
	baytrail,

};



struct dw_scl_sda_cfg {

	u32 ss_hcnt;

	u32 fs_hcnt;

	u32 ss_lcnt;

	u32 fs_lcnt;

	u32 sda_hold;

};



struct dw_pci_controller {

	u32 bus_num;

	u32 bus_cfg;
@@ -65,6 +73,7 @@ struct dw_pci_controller { 
	u32 rx_fifo_depth;

	u32 clk_khz;

	u32 functionality;

	struct dw_scl_sda_cfg *scl_sda_cfg;

};



#define INTEL_MID_STD_CFG  (DW_IC_CON_MASTER |			\
@@ -77,6 +86,15 @@ struct dw_pci_controller { 
					I2C_FUNC_SMBUS_WORD_DATA |	\

					I2C_FUNC_SMBUS_I2C_BLOCK)



/* BayTrail HCNT/LCNT/SDA hold time */

static struct dw_scl_sda_cfg byt_config = {

	.ss_hcnt = 0x200,

	.fs_hcnt = 0x55,

	.ss_lcnt = 0x200,

	.fs_lcnt = 0x99,

	.sda_hold = 0x6,

};



static struct  dw_pci_controller  dw_pci_controllers[] = {

	[moorestown_0] = {

		.bus_num     = 0,
@@ -148,6 +166,7 @@ static struct dw_pci_controller dw_pci_controllers[] = { 
		.rx_fifo_depth = 32,

		.clk_khz = 100000,

		.functionality = I2C_FUNC_10BIT_ADDR,

		.scl_sda_cfg = &byt_config,

	},

};

static struct i2c_algorithm i2c_dw_algo = {
@@ -187,6 +206,7 @@ static int i2c_dw_pci_probe(struct pci_dev *pdev, 
	struct i2c_adapter *adap;

	int r;

	struct  dw_pci_controller *controller;

	struct dw_scl_sda_cfg *cfg;



	if (id->driver_data >= ARRAY_SIZE(dw_pci_controllers)) {

		dev_err(&pdev->dev, "%s: invalid driver data %ld\n", __func__,
@@ -224,6 +244,14 @@ static int i2c_dw_pci_probe(struct pci_dev *pdev, 
				DW_DEFAULT_FUNCTIONALITY;



	dev->master_cfg =  controller->bus_cfg;

	if (controller->scl_sda_cfg) {

		cfg = controller->scl_sda_cfg;

		dev->ss_hcnt = cfg->ss_hcnt;

		dev->fs_hcnt = cfg->fs_hcnt;

		dev->ss_lcnt = cfg->ss_lcnt;

		dev->fs_lcnt = cfg->fs_lcnt;

		dev->sda_hold_time = cfg->sda_hold;

	}



	pci_set_drvdata(pdev, dev);