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Date: Mon, 21 Dec 2020 18:04:13 +0530
From: rojay@...eaurora.org
To: Akash Asthana <akashast@...eaurora.org>
Cc: wsa@...nel.org, swboyd@...omium.org, dianders@...omium.org,
saiprakash.ranjan@...eaurora.org, gregkh@...uxfoundation.org,
mka@...omium.org, msavaliy@....qualcomm.com, skakit@...eaurora.org,
vkaur@...eaurora.org, pyarlaga@...eaurora.org,
rnayak@...eaurora.org, agross@...nel.org,
bjorn.andersson@...aro.org, linux-arm-msm@...r.kernel.org,
linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org,
sumit.semwal@...aro.org, linux-media@...r.kernel.org
Subject: Re: [RESEND PATCH V6 1/2] i2c: i2c-qcom-geni: Store DMA mapping data
in geni_i2c_dev struct
On 2020-12-09 18:29, Akash Asthana wrote:
> Hi Roja,
>
> On 12/3/2020 4:01 PM, Roja Rani Yarubandi wrote:
>> Store DMA mapping data in geni_i2c_dev struct to enhance DMA mapping
>> data scope. For example during shutdown callback to unmap DMA mapping,
>> this stored DMA mapping data can be used to call geni_se_tx_dma_unprep
>> and geni_se_rx_dma_unprep functions.
>>
>> Add two helper functions geni_i2c_rx_msg_cleanup and
>> geni_i2c_tx_msg_cleanup to unwrap the things after rx/tx FIFO/DMA
>> transfers, so that the same can be used in geni_i2c_stop_xfer()
>> function during shutdown callback.
>>
>> Signed-off-by: Roja Rani Yarubandi <rojay@...eaurora.org>
>> ---
>> Changes in V5:
>> - As per Stephen's comments separated this patch from shutdown
>> callback patch, gi2c->cur = NULL is not removed from
>> geni_i2c_abort_xfer(), and made a copy of gi2c->cur and passed
>> to cleanup functions.
>>
>> Changes in V6:
>> - Added spin_lock/unlock in geni_i2c_rx_msg_cleanup() and
>> geni_i2c_tx_msg_cleanup() functions.
>>
>> drivers/i2c/busses/i2c-qcom-geni.c | 69
>> +++++++++++++++++++++++-------
>> 1 file changed, 53 insertions(+), 16 deletions(-)
>>
>> diff --git a/drivers/i2c/busses/i2c-qcom-geni.c
>> b/drivers/i2c/busses/i2c-qcom-geni.c
>> index dce75b85253c..bfbc80f65006 100644
>> --- a/drivers/i2c/busses/i2c-qcom-geni.c
>> +++ b/drivers/i2c/busses/i2c-qcom-geni.c
>> @@ -86,6 +86,9 @@ struct geni_i2c_dev {
>> u32 clk_freq_out;
>> const struct geni_i2c_clk_fld *clk_fld;
>> int suspended;
>> + void *dma_buf;
>> + size_t xfer_len;
>> + dma_addr_t dma_addr;
>> };
>> struct geni_i2c_err_log {
>> @@ -348,14 +351,49 @@ static void geni_i2c_tx_fsm_rst(struct
>> geni_i2c_dev *gi2c)
>> dev_err(gi2c->se.dev, "Timeout resetting TX_FSM\n");
>> }
>> +static void geni_i2c_rx_msg_cleanup(struct geni_i2c_dev *gi2c,
>> + struct i2c_msg *cur)
>> +{
>> + struct geni_se *se = &gi2c->se;
>> + unsigned long flags;
>> +
>> + spin_lock_irqsave(&gi2c->lock, flags);
>> + gi2c->cur_rd = 0;
>> + if (gi2c->dma_buf) {
>> + if (gi2c->err)
>> + geni_i2c_rx_fsm_rst(gi2c);
>
> Which race we are trying to avoid here by holding spinlock?
>
Thought that race might occur with "cur" here.
> We cannot call any sleeping API by holding spinlock,
> geni_i2c_rx_fsm_rst calls *wait-for-completion*, which is a sleeping
> call.
>
Fixed this.
>> + geni_se_rx_dma_unprep(se, gi2c->dma_addr, gi2c->xfer_len);
>> + i2c_put_dma_safe_msg_buf(gi2c->dma_buf, cur, !gi2c->err);
>> + }
>> + spin_unlock_irqrestore(&gi2c->lock, flags);
>> +}
>> +
>> +static void geni_i2c_tx_msg_cleanup(struct geni_i2c_dev *gi2c,
>> + struct i2c_msg *cur)
>> +{
>> + struct geni_se *se = &gi2c->se;
>> + unsigned long flags;
>> +
>> + spin_lock_irqsave(&gi2c->lock, flags);
>> + gi2c->cur_wr = 0;
>> + if (gi2c->dma_buf) {
>> + if (gi2c->err)
>> + geni_i2c_tx_fsm_rst(gi2c);
>
> Same here
>
> Regards,
>
> Akash
>
>> + geni_se_tx_dma_unprep(se, gi2c->dma_addr, gi2c->xfer_len);
>> + i2c_put_dma_safe_msg_buf(gi2c->dma_buf, cur, !gi2c->err);
>> + }
>> + spin_unlock_irqrestore(&gi2c->lock, flags);
>> +}
>> +
>> static int geni_i2c_rx_one_msg(struct geni_i2c_dev *gi2c, struct
>> i2c_msg *msg,
>> u32 m_param)
>> {
>> - dma_addr_t rx_dma;
>> + dma_addr_t rx_dma = 0;
>> unsigned long time_left;
>> void *dma_buf = NULL;
>> struct geni_se *se = &gi2c->se;
>> size_t len = msg->len;
>> + struct i2c_msg *cur;
>> if (!of_machine_is_compatible("lenovo,yoga-c630"))
>> dma_buf = i2c_get_dma_safe_msg_buf(msg, 32);
>> @@ -372,19 +410,18 @@ static int geni_i2c_rx_one_msg(struct
>> geni_i2c_dev *gi2c, struct i2c_msg *msg,
>> geni_se_select_mode(se, GENI_SE_FIFO);
>> i2c_put_dma_safe_msg_buf(dma_buf, msg, false);
>> dma_buf = NULL;
>> + } else {
>> + gi2c->xfer_len = len;
>> + gi2c->dma_addr = rx_dma;
>> + gi2c->dma_buf = dma_buf;
>> }
>> + cur = gi2c->cur;
>> time_left = wait_for_completion_timeout(&gi2c->done, XFER_TIMEOUT);
>> if (!time_left)
>> geni_i2c_abort_xfer(gi2c);
>> - gi2c->cur_rd = 0;
>> - if (dma_buf) {
>> - if (gi2c->err)
>> - geni_i2c_rx_fsm_rst(gi2c);
>> - geni_se_rx_dma_unprep(se, rx_dma, len);
>> - i2c_put_dma_safe_msg_buf(dma_buf, msg, !gi2c->err);
>> - }
>> + geni_i2c_rx_msg_cleanup(gi2c, cur);
>> return gi2c->err;
>> }
>> @@ -392,11 +429,12 @@ static int geni_i2c_rx_one_msg(struct
>> geni_i2c_dev *gi2c, struct i2c_msg *msg,
>> static int geni_i2c_tx_one_msg(struct geni_i2c_dev *gi2c, struct
>> i2c_msg *msg,
>> u32 m_param)
>> {
>> - dma_addr_t tx_dma;
>> + dma_addr_t tx_dma = 0;
>> unsigned long time_left;
>> void *dma_buf = NULL;
>> struct geni_se *se = &gi2c->se;
>> size_t len = msg->len;
>> + struct i2c_msg *cur;
>> if (!of_machine_is_compatible("lenovo,yoga-c630"))
>> dma_buf = i2c_get_dma_safe_msg_buf(msg, 32);
>> @@ -413,22 +451,21 @@ static int geni_i2c_tx_one_msg(struct
>> geni_i2c_dev *gi2c, struct i2c_msg *msg,
>> geni_se_select_mode(se, GENI_SE_FIFO);
>> i2c_put_dma_safe_msg_buf(dma_buf, msg, false);
>> dma_buf = NULL;
>> + } else {
>> + gi2c->xfer_len = len;
>> + gi2c->dma_addr = tx_dma;
>> + gi2c->dma_buf = dma_buf;
>> }
>> if (!dma_buf) /* Get FIFO IRQ */
>> writel_relaxed(1, se->base + SE_GENI_TX_WATERMARK_REG);
>> + cur = gi2c->cur;
>> time_left = wait_for_completion_timeout(&gi2c->done, XFER_TIMEOUT);
>> if (!time_left)
>> geni_i2c_abort_xfer(gi2c);
>> - gi2c->cur_wr = 0;
>> - if (dma_buf) {
>> - if (gi2c->err)
>> - geni_i2c_tx_fsm_rst(gi2c);
>> - geni_se_tx_dma_unprep(se, tx_dma, len);
>> - i2c_put_dma_safe_msg_buf(dma_buf, msg, !gi2c->err);
>> - }
>> + geni_i2c_tx_msg_cleanup(gi2c, cur);
>> return gi2c->err;
>> }
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