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Message-ID: <20190726204242.GA3163@archbox>
Date: Fri, 26 Jul 2019 13:42:42 -0700
From: Moritz Fischer <mdf@...nel.org>
To: thor.thayer@...ux.intel.com
Cc: mdf@...nel.org, richard.gong@...ux.intel.com, agust@...x.de,
linux-fpga@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCHv3 3/3] fpga: altera-cvp: Add Stratix10 (V2) Support
On Thu, Jul 25, 2019 at 10:16:48AM -0500, thor.thayer@...ux.intel.com wrote:
> From: Thor Thayer <thor.thayer@...ux.intel.com>
>
> Add Stratix10 specific functions that use a credit mechanism
> to throttle data to the CvP FIFOs. Add a private structure
> with function pointers for V1 vs V2 functions.
>
> Signed-off-by: Thor Thayer <thor.thayer@...ux.intel.com>
> ---
> v2 Remove inline function declaration
> Reverse Christmas Tree format for local variables
> Remove mask from credit calculation
> Add commment for the delay(1) function in wait_for_credit()
> v3 Fix return code of abstraction function
> Move reset of current_credit_byte to clear_state().
> Check return code of credit register read in wait_for_credit()
> Check return code of clear_state read/write register.
> ---
> drivers/fpga/altera-cvp.c | 193 ++++++++++++++++++++++++++++++++++++++++++----
> 1 file changed, 178 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/fpga/altera-cvp.c b/drivers/fpga/altera-cvp.c
> index b08c0fd353ba..6bf7462af4f3 100644
> --- a/drivers/fpga/altera-cvp.c
> +++ b/drivers/fpga/altera-cvp.c
> @@ -43,16 +43,32 @@
> #define VSE_CVP_PROG_CTRL 0x2c /* 32bit */
> #define VSE_CVP_PROG_CTRL_CONFIG BIT(0)
> #define VSE_CVP_PROG_CTRL_START_XFER BIT(1)
> +#define VSE_CVP_PROG_CTRL_MASK GENMASK(1, 0)
>
> #define VSE_UNCOR_ERR_STATUS 0x34 /* 32bit */
> #define VSE_UNCOR_ERR_CVP_CFG_ERR BIT(5) /* CVP_CONFIG_ERROR_LATCHED */
>
> +/* V2 Defines */
> +#define VSE_CVP_TX_CREDITS 0x49 /* 8bit */
> +
> +#define CREDIT_TIMEOUT_US 20000
> +#define V2_POLL_TIMEOUT_US 1000000
> +#define V2_USER_TIMEOUT_US 500000
> +
> +#define V1_POLL_TIMEOUT_US 10
> +
> #define DRV_NAME "altera-cvp"
> #define ALTERA_CVP_MGR_NAME "Altera CvP FPGA Manager"
>
> +/* Write block sizes */
> +#define ALTERA_CVP_V1_SIZE 4
> +#define ALTERA_CVP_V2_SIZE 4096
> +
> /* Optional CvP config error status check for debugging */
> static bool altera_cvp_chkcfg;
>
> +struct cvp_priv;
> +
> struct altera_cvp_conf {
> struct fpga_manager *mgr;
> struct pci_dev *pci_dev;
> @@ -60,9 +76,27 @@ struct altera_cvp_conf {
> void (*write_data)(struct altera_cvp_conf *, u32);
> char mgr_name[64];
> u8 numclks;
> + u8 current_credit_byte;
> u32 vsec_offset;
> + const struct cvp_priv *priv;
> };
>
> +struct cvp_priv {
> + void (*switch_clk)(struct altera_cvp_conf *conf);
> + int (*clear_state)(struct altera_cvp_conf *conf);
> + int (*wait_credit)(struct fpga_manager *mgr, u32 blocks);
> + int block_size;
> + int poll_time_us;
> + int user_time_us;
> +};
> +
> +static int altera_read_config_byte(struct altera_cvp_conf *conf,
> + int where, u8 *val)
> +{
> + return pci_read_config_byte(conf->pci_dev, conf->vsec_offset + where,
> + val);
> +}
> +
> static int altera_read_config_dword(struct altera_cvp_conf *conf,
> int where, u32 *val)
> {
> @@ -158,6 +192,78 @@ static int altera_cvp_chk_error(struct fpga_manager *mgr, size_t bytes)
> return 0;
> }
>
> +/*
> + * CvP Version2 Functions
> + * Recent Intel FPGAs use a credit mechanism to throttle incoming
> + * bitstreams and a different method of clearing the state.
> + */
> +
> +static int altera_cvp_v2_clear_state(struct altera_cvp_conf *conf)
> +{
> + u32 val;
> + int ret;
> +
> + conf->current_credit_byte = 0;
> +
> + /* Clear the START_XFER and CVP_CONFIG bits */
> + ret = altera_read_config_dword(conf, VSE_CVP_PROG_CTRL, &val);
> + if (ret) {
> + dev_err(&conf->pci_dev->dev,
> + "Error reading CVP Program Control Register\n");
> + return ret;
> + }
> +
> + val &= ~VSE_CVP_PROG_CTRL_MASK;
> + ret = altera_write_config_dword(conf, VSE_CVP_PROG_CTRL, val);
> + if (ret) {
> + dev_err(&conf->pci_dev->dev,
> + "Error writing CVP Program Control Register\n");
> + return ret;
> + }
> +
> + return altera_cvp_wait_status(conf, VSE_CVP_STATUS_CFG_RDY, 0,
> + conf->priv->poll_time_us);
> +}
> +
> +static int altera_cvp_v2_wait_for_credit(struct fpga_manager *mgr,
> + u32 blocks)
> +{
> + struct altera_cvp_conf *conf = mgr->priv;
> + u8 val, delta_credit;
> + u32 count = 0;
> + int ret;
> +
> + do {
> + ret = altera_read_config_byte(conf, VSE_CVP_TX_CREDITS, &val);
> + if (ret) {
> + dev_err(&conf->pci_dev->dev,
> + "Error reading CVP Credit Register\n");
> + return ret;
> + }
> +
> + delta_credit = val - conf->current_credit_byte;
How about 'space' or something similar ... instead of delta_credit
> +
> + ret = altera_cvp_chk_error(mgr, blocks * ALTERA_CVP_V2_SIZE);
> + if (ret) {
> + dev_err(&conf->pci_dev->dev,
> + "CE Bit error credits host[0x%x]:dev[0x%x]\n",
> + conf->current_credit_byte, val);
> + return -EAGAIN;
> + }
> +
> + if (count++ >= CREDIT_TIMEOUT_US) {
If you invert the logic here you can run your loop with while (!space &&
timeout--), that might make it simpler.
> + dev_err(&conf->pci_dev->dev,
> + "Timeout waiting for credit\n");
> + return -ETIMEDOUT;
> + }
> +
> + /* Limit the traffic & ensure a timeout in usec */
> + udelay(1);
Does this need to be 1us or can this be a usleep_range()?
> + } while (!delta_credit);
> +
> + return 0;
> +}
> +
> static int altera_cvp_send_block(struct altera_cvp_conf *conf,
> const u32 *data, size_t len)
> {
> @@ -199,10 +305,12 @@ static int altera_cvp_teardown(struct fpga_manager *mgr,
> * - set CVP_NUMCLKS to 1 and then issue CVP_DUMMY_WR dummy
> * writes to the HIP
> */
> - altera_cvp_dummy_write(conf); /* from CVP clock to internal clock */
> + if (conf->priv->switch_clk)
> + conf->priv->switch_clk(conf);
>
> /* STEP 15 - poll CVP_CONFIG_READY bit for 0 with 10us timeout */
> - ret = altera_cvp_wait_status(conf, VSE_CVP_STATUS_CFG_RDY, 0, 10);
> + ret = altera_cvp_wait_status(conf, VSE_CVP_STATUS_CFG_RDY, 0,
> + conf->priv->poll_time_us);
> if (ret)
> dev_err(&mgr->dev, "CFG_RDY == 0 timeout\n");
>
> @@ -264,7 +372,16 @@ static int altera_cvp_write_init(struct fpga_manager *mgr,
> * STEP 3
> * - set CVP_NUMCLKS to 1 and issue CVP_DUMMY_WR dummy writes to the HIP
> */
> - altera_cvp_dummy_write(conf);
> + if (conf->priv->switch_clk)
> + conf->priv->switch_clk(conf);
> +
> + if (conf->priv->clear_state) {
> + ret = conf->priv->clear_state(conf);
> + if (ret) {
> + dev_err(&mgr->dev, "Problem clearing out state\n");
> + return ret;
> + }
> + }
>
> /* STEP 4 - set CVP_CONFIG bit */
> altera_read_config_dword(conf, VSE_CVP_PROG_CTRL, &val);
> @@ -272,9 +389,10 @@ static int altera_cvp_write_init(struct fpga_manager *mgr,
> val |= VSE_CVP_PROG_CTRL_CONFIG;
> altera_write_config_dword(conf, VSE_CVP_PROG_CTRL, val);
>
> - /* STEP 5 - poll CVP_CONFIG READY for 1 with 10us timeout */
> + /* STEP 5 - poll CVP_CONFIG READY for 1 with timeout */
> ret = altera_cvp_wait_status(conf, VSE_CVP_STATUS_CFG_RDY,
> - VSE_CVP_STATUS_CFG_RDY, 10);
> + VSE_CVP_STATUS_CFG_RDY,
> + conf->priv->poll_time_us);
> if (ret) {
> dev_warn(&mgr->dev, "CFG_RDY == 1 timeout\n");
> return ret;
> @@ -284,7 +402,16 @@ static int altera_cvp_write_init(struct fpga_manager *mgr,
> * STEP 6
> * - set CVP_NUMCLKS to 1 and issue CVP_DUMMY_WR dummy writes to the HIP
> */
> - altera_cvp_dummy_write(conf);
> + if (conf->priv->switch_clk)
> + conf->priv->switch_clk(conf);
> +
> + if (altera_cvp_chkcfg) {
> + ret = altera_cvp_chk_error(mgr, 0);
> + if (ret) {
> + dev_warn(&mgr->dev, "CFG_RDY == 1 timeout\n");
> + return ret;
> + }
> + }
>
> /* STEP 7 - set START_XFER */
> altera_read_config_dword(conf, VSE_CVP_PROG_CTRL, &val);
> @@ -292,11 +419,12 @@ static int altera_cvp_write_init(struct fpga_manager *mgr,
> altera_write_config_dword(conf, VSE_CVP_PROG_CTRL, val);
>
> /* STEP 8 - start transfer (set CVP_NUMCLKS for bitstream) */
> - altera_read_config_dword(conf, VSE_CVP_MODE_CTRL, &val);
> - val &= ~VSE_CVP_MODE_CTRL_NUMCLKS_MASK;
> - val |= conf->numclks << VSE_CVP_MODE_CTRL_NUMCLKS_OFF;
> - altera_write_config_dword(conf, VSE_CVP_MODE_CTRL, val);
> -
> + if (conf->priv->switch_clk) {
> + altera_read_config_dword(conf, VSE_CVP_MODE_CTRL, &val);
> + val &= ~VSE_CVP_MODE_CTRL_NUMCLKS_MASK;
> + val |= conf->numclks << VSE_CVP_MODE_CTRL_NUMCLKS_OFF;
> + altera_write_config_dword(conf, VSE_CVP_MODE_CTRL, val);
> + }
> return 0;
> }
>
> @@ -314,15 +442,26 @@ static int altera_cvp_write(struct fpga_manager *mgr, const char *buf,
> done = 0;
>
> while (remaining) {
> - if (remaining >= sizeof(u32))
> - len = sizeof(u32);
> + /* Use credit throttling if available */
> + if (conf->priv->wait_credit) {
> + status = conf->priv->wait_credit(mgr, done);
> + if (status) {
> + dev_err(&conf->pci_dev->dev,
> + "Wait Credit ERR: 0x%x\n", status);
> + return status;
> + }
> + }
> +
> + if (remaining >= conf->priv->block_size)
> + len = conf->priv->block_size;
> else
> len = remaining;
len = min(conf->priv->block_size, remaining) seems easier.
>
> altera_cvp_send_block(conf, data, len);
> - data++;
> + data += len / sizeof(u32);
> done += len;
> remaining -= len;
> + conf->current_credit_byte++;
I'll need to take another look at this loop :) This is confusing
>
> /*
> * STEP 10 (optional) and STEP 11
> @@ -372,7 +511,8 @@ static int altera_cvp_write_complete(struct fpga_manager *mgr,
>
> /* STEP 18 - poll PLD_CLK_IN_USE and USER_MODE bits */
> mask = VSE_CVP_STATUS_PLD_CLK_IN_USE | VSE_CVP_STATUS_USERMODE;
> - ret = altera_cvp_wait_status(conf, mask, mask, TIMEOUT_US);
> + ret = altera_cvp_wait_status(conf, mask, mask,
> + conf->priv->user_time_us);
> if (ret)
> dev_err(&mgr->dev, "PLD_CLK_IN_USE|USERMODE timeout\n");
>
> @@ -386,6 +526,24 @@ static const struct fpga_manager_ops altera_cvp_ops = {
> .write_complete = altera_cvp_write_complete,
> };
>
> +static const struct cvp_priv cvp_priv_v1 = {
> + .switch_clk = altera_cvp_dummy_write,
> + .clear_state = NULL,
> + .wait_credit = NULL,
static variables (and structs) would get set to 0 anyways,
so the = NULL parts aren't technically required.
I think if this were a single static variable, you'd get a checkpatch
warning here.
> + .block_size = ALTERA_CVP_V1_SIZE,
> + .poll_time_us = V1_POLL_TIMEOUT_US,
> + .user_time_us = TIMEOUT_US,
> +};
> +
> +static const struct cvp_priv cvp_priv_v2 = {
> + .switch_clk = NULL,
> + .clear_state = altera_cvp_v2_clear_state,
> + .wait_credit = altera_cvp_v2_wait_for_credit,
> + .block_size = ALTERA_CVP_V2_SIZE,
> + .poll_time_us = V2_POLL_TIMEOUT_US,
> + .user_time_us = V2_USER_TIMEOUT_US,
> +};
> +
> static ssize_t chkcfg_show(struct device_driver *dev, char *buf)
> {
> return snprintf(buf, 3, "%d\n", altera_cvp_chkcfg);
> @@ -488,6 +646,11 @@ static int altera_cvp_probe(struct pci_dev *pdev,
> conf->pci_dev = pdev;
> conf->write_data = altera_cvp_write_data_iomem;
>
> + if (conf->vsec_offset == 0x200)
Can you give that 0x200 a name?
> + conf->priv = &cvp_priv_v1;
> + else
> + conf->priv = &cvp_priv_v2;
> +
> conf->map = pci_iomap(pdev, CVP_BAR, 0);
> if (!conf->map) {
> dev_warn(&pdev->dev, "Mapping CVP BAR failed\n");
> --
> 2.7.4
>
Thanks,
Moritz
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