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Message-ID: <db1b8b4b-3a17-9e1a-d12d-7c954e9e5ff9@linux.intel.com>
Date: Mon, 29 Jul 2019 09:08:24 -0500
From: Thor Thayer <thor.thayer@...ux.intel.com>
To: Moritz Fischer <mdf@...nel.org>
Cc: 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
Hi Moritz,
On 7/26/19 3:42 PM, Moritz Fischer wrote:
> 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
Sure. I'll rename it.
>> +
>> + 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.
OK. I will change it.
>> + 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()?
Yes, I can change it to a usleep_range(10,11) but probably not
unconditional since an empty FIFO doesn't need that delay.
>> + } 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.
Yes, much better. I'll make the change.
>>
>> 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
I'll take another look at this loop. I'm basically sending blocks of
data (4K in the case of V2 or 1 word in the case of V1), moving the
pointer to the next block, and decrementing the byte counter by the # of
bytes that were sent.
>>
>> /*
>> * 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.
OK. I will remove them.
>> + .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 nameSure.
Thanks for reviewing!
>> + 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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