Hi Laurent,
On 17/06/2020 11:05, Laurent Pinchart wrote:
> Hi Kieran,
>
> On Wed, Jun 17, 2020 at 10:56:29AM +0100, Kieran Bingham wrote:
>> On 15/06/2020 00:59, Laurent Pinchart wrote:
>>> The external pixel rate is retrieved when starting the camerarx and only
>>> used then. There's no need to store it in the cal_camerarx structure, it
>>> can be returned by cal_camerarx_get_external_info() and explicitly
>>> passed to cal_camerarx_config().
>>>
>>> While at it, rename cal_camerarx_get_external_info() to
>>> cal_camerarx_get_external_rate() to better reflect the function's
>>> purpose.
>>>
>>> Signed-off-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
>>> ---
>>> drivers/media/platform/ti-vpe/cal.c | 24 ++++++++++++------------
>>> 1 file changed, 12 insertions(+), 12 deletions(-)
>>>
>>> diff --git a/drivers/media/platform/ti-vpe/cal.c b/drivers/media/platform/ti-vpe/cal.c
>>> index 8326db0e4197..a11457909134 100644
>>> --- a/drivers/media/platform/ti-vpe/cal.c
>>> +++ b/drivers/media/platform/ti-vpe/cal.c
>>> @@ -272,7 +272,6 @@ struct cal_camerarx {
>>> struct v4l2_fwnode_endpoint endpoint;
>>> struct device_node *sensor_node;
>>> struct v4l2_subdev *sensor;
>>> - unsigned int external_rate;
>>
>> Here, external_rate is 32 bit,
>>
>>> };
>>>
>>> struct cal_dev {
>>> @@ -481,9 +480,10 @@ static void cal_quickdump_regs(struct cal_dev *cal)
>>> * ------------------------------------------------------------------
>>> */
>>>
>>> -static int cal_camerarx_get_external_info(struct cal_camerarx *phy)
>>> +static s64 cal_camerarx_get_external_rate(struct cal_camerarx *phy)
>>> {
>>> struct v4l2_ctrl *ctrl;
>>> + s64 rate;
>>
>> and now it becomes a 64 bit value.
>>
>>>
>>> if (!phy->sensor)
>>> return -ENODEV;
>>> @@ -495,10 +495,10 @@ static int cal_camerarx_get_external_info(struct cal_camerarx *phy)
>>> return -EPIPE;
>>> }
>>>
>>> - phy->external_rate = v4l2_ctrl_g_ctrl_int64(ctrl);
>>> - phy_dbg(3, phy, "sensor Pixel Rate: %u\n", phy->external_rate);
>>> + rate = v4l2_ctrl_g_ctrl_int64(ctrl);
>>> + phy_dbg(3, phy, "sensor Pixel Rate: %llu\n", rate);
>>>
>>> - return 0;
>>> + return rate;
>>> }
>>>
>>> static void cal_camerarx_lane_config(struct cal_camerarx *phy)
>>> @@ -554,7 +554,7 @@ static void cal_camerarx_disable(struct cal_camerarx *phy)
>>> #define TCLK_MISS 1
>>> #define TCLK_SETTLE 14
>>>
>>> -static void cal_camerarx_config(struct cal_camerarx *phy,
>>> +static void cal_camerarx_config(struct cal_camerarx *phy, s64 external_rate,
>>> const struct cal_fmt *fmt)
>>> {
>>> unsigned int reg0, reg1;
>>> @@ -566,7 +566,7 @@ static void cal_camerarx_config(struct cal_camerarx *phy,
>>>
>>> /* DPHY timing configuration */
>>> /* CSI-2 is DDR and we only count used lanes. */
>>> - csi2_ddrclk_khz = phy->external_rate / 1000
>>> + csi2_ddrclk_khz = external_rate / 1000
>>> / (2 * num_lanes) * fmt->bpp;
>>
>> Which causes this calculation to fail on 32 bit ARM builds.
>> (I'm building for the DRA76-EVM).
>
> Oops :-/
>
>> I've got the following fix up on the top of your tree to solve this, but
>> I'm not particularly happy about having to break the calculation up (and
>> re-use external_rate) though the use of do_div.
>>
>> From ca6ce335a852e34364bc45cb4240f703e4ea4248 Mon Sep 17 00:00:00 2001
>> From: Kieran Bingham <kieran.bingham@xxxxxxxxxxxxxxxx>
>> Date: Tue, 16 Jun 2020 16:19:04 +0100
>> Subject: [PATCH] media: ti-vpe: cal: Use do_div() for 64 bit operations
>>
>> Support building the CAL driver on arm32 bit targets by updating the
>> CSI2 clock calculation (which uses a signed 64 bit input value from
>> the sensors pixel clock rate) to use the do_div() helpers.
>>
>> The calculation is split into distinct parts to maintain
>> order of operations while making use of the do_div macro and further
>> re-ordered to convert to kHz at the end to maintain precision.
>>
>> Signed-off-by: Kieran Bingham <kieran.bingham@xxxxxxxxxxxxxxxx>
>> ---
>> drivers/media/platform/ti-vpe/cal-camerarx.c | 22 +++++++++++++++++---
>> 1 file changed, 19 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/media/platform/ti-vpe/cal-camerarx.c
>> b/drivers/media/platform/ti-vpe/cal-camerarx.c
>> index 014ca46509db..0ef19a516902 100644
>> --- a/drivers/media/platform/ti-vpe/cal-camerarx.c
>> +++ b/drivers/media/platform/ti-vpe/cal-camerarx.c
>> @@ -126,9 +126,25 @@ static void cal_camerarx_config(struct cal_camerarx
>> *phy, s64 external_rate)
>> u32 num_lanes = mipi_csi2->num_data_lanes;
>>
>> /* DPHY timing configuration */
>> - /* CSI-2 is DDR and we only count used lanes. */
>> - csi2_ddrclk_khz = external_rate / 1000
>> - / (2 * num_lanes) * phy->fmtinfo->bpp;
>> +
>> + /*
>> + * CSI-2 is DDR and we only count used lanes.
>> + *
>> + * csi2_ddrclk_khz = external_rate / 1000
>> + * / (2 * num_lanes) * phy->fmtinfo->bpp;
>> + *
>> + * The equation is broken into separate statements to maintain
>> + * order of operations, and conversion to kHz is done last to
>> + * keep precision.
>> + *
>> + * The 64 bit external_rate is modified during this equation and
>> + * contains the result, not the original after calculation.
>> + */
>> + do_div(external_rate, 2 * num_lanes);
>> + external_rate *= phy->fmtinfo->bpp;
>> + do_div(external_rate, 1000);
>> + csi2_ddrclk_khz = external_rate;
>
> How about
>
> external_rate *= phy->fmtinfo->bpp;
> do_div(external_rate, 2 * num_lanes * 1000);
Ah yes, that looks better indeed, and keeps the improved integer precision.
I believe the s64 external_rate should cope with the * bpp operation
easily too, so I don't think there's any risk of an overflow there.
Squash it ;-)
--
Kieran
>
>> +
>> phy_dbg(1, phy, "csi2_ddrclk_khz: %d\n", csi2_ddrclk_khz);
>>
>> /* THS_TERM: Programmed value = floor(20 ns/DDRClk period) */
>> --
>> 2.25.1
>>
>>
>> If you have a better way to correctly calculate the rate (also noting
>> that I moved the /1000 to the end, I'm not sure if that's more correct,
>> or makes it stop following what the hardware would do) - please update
>> accordingly, or feel free to squash this patch in as you wish.
>>
>>
>> With the calculation corrected:
>>
>> Reviewed-by: Kieran Bingham <kieran.bingham@xxxxxxxxxxxxxxxx>
>>
>> --
>> Kieran
>>
>>
>>> phy_dbg(1, phy, "csi2_ddrclk_khz: %d\n", csi2_ddrclk_khz);
>>>
>>> @@ -667,13 +667,14 @@ static void cal_camerarx_wait_stop_state(struct cal_camerarx *phy)
>>> static int cal_camerarx_start(struct cal_camerarx *phy,
>>> const struct cal_fmt *fmt)
>>> {
>>> + s64 external_rate;
>>> u32 sscounter;
>>> u32 val;
>>> int ret;
>>>
>>> - ret = cal_camerarx_get_external_info(phy);
>>> - if (ret < 0)
>>> - return ret;
>>> + external_rate = cal_camerarx_get_external_rate(phy);
>>> + if (external_rate < 0)
>>> + return external_rate;
>>>
>>> ret = v4l2_subdev_call(phy->sensor, core, s_power, 1);
>>> if (ret < 0 && ret != -ENOIOCTLCMD && ret != -ENODEV) {
>>> @@ -719,7 +720,7 @@ static int cal_camerarx_start(struct cal_camerarx *phy,
>>> reg_read(phy, CAL_CSI2_PHY_REG0);
>>>
>>> /* Program the PHY timing parameters. */
>>> - cal_camerarx_config(phy, fmt);
>>> + cal_camerarx_config(phy, external_rate, fmt);
>>>
>>> /*
>>> * b. Assert the FORCERXMODE signal.
>>> @@ -1034,7 +1035,6 @@ static struct cal_camerarx *cal_camerarx_create(struct cal_dev *cal,
>>>
>>> phy->cal = cal;
>>> phy->instance = instance;
>>> - phy->external_rate = 192000000;
>>>
>>> phy->res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
>>> (instance == 0) ?
>
--
Regards
--
Kieran
