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Date: Thu, 15 Dec 2022 20:46:42 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Kuogee Hsieh <quic_khsieh@...cinc.com>, robdclark@...il.com,
sean@...rly.run, swboyd@...omium.org, dianders@...omium.org,
vkoul@...nel.org, daniel@...ll.ch, airlied@...il.com,
agross@...nel.org, andersson@...nel.org
Cc: quic_abhinavk@...cinc.com, quic_sbillaka@...cinc.com,
freedreno@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] drm/msm/dp: do not complete dp_aux_cmd_fifo_tx() if
irq is not for aux transfer
On 15/12/2022 20:32, Kuogee Hsieh wrote:
> There are 3 possible interrupt sources are handled by DP controller,
> HPDstatus, Controller state changes and Aux read/write transaction.
> At every irq, DP controller have to check isr status of every interrupt
> sources and service the interrupt if its isr status bits shows interrupts
> are pending. There is potential race condition may happen at current aux
> isr handler implementation since it is always complete dp_aux_cmd_fifo_tx()
> even irq is not for aux read or write transaction. This may cause aux read
> transaction return premature if host aux data read is in the middle of
> waiting for sink to complete transferring data to host while irq happen.
> This will cause host's receiving buffer contains unexpected data. This
> patch fixes this problem by checking aux isr and return immediately at
> aux isr handler if there are no any isr status bits set.
>
> Current there is a bug report regrading eDP edid corruption happen during
> system booting up. After lengthy debugging to found that VIDEO_READY
> interrupt was continuously firing during system booting up which cause
> dp_aux_isr() to complete dp_aux_cmd_fifo_tx() prematurely to retrieve data
> from aux hardware buffer which is not yet contains complete data transfer
> from sink. This cause edid corruption.
>
> Follows are the signature at kernel logs when problem happen,
> EDID has corrupt header
> panel-simple-dp-aux aux-aea0000.edp: Couldn't identify panel via EDID
> panel-simple-dp-aux aux-aea0000.edp: error -EIO: Couldn't detect panel nor find a fallback
>
> Changes in v2:
> -- do complete if (ret == IRQ_HANDLED) ay dp-aux_isr()
> -- add more commit text
Usually it's a single dash.
>
> Fixes: c943b4948b58 ("drm/msm/dp: add displayPort driver support")
>
> Signed-off-by: Kuogee Hsieh <quic_khsieh@...cinc.com>
There should be no empty lines between the tags.
> Tested-by: Douglas Anderson <dianders@...omium.org>
> Reviewed-by: Abhinav Kumar <quic_abhinavk@...cinc.com>
> ---
> drivers/gpu/drm/msm/dp/dp_aux.c | 87 +++++++++++++++++++++++++++++------------
> 1 file changed, 63 insertions(+), 24 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/dp/dp_aux.c b/drivers/gpu/drm/msm/dp/dp_aux.c
> index d030a93..f31e5c1 100644
> --- a/drivers/gpu/drm/msm/dp/dp_aux.c
> +++ b/drivers/gpu/drm/msm/dp/dp_aux.c
> @@ -162,45 +162,78 @@ static ssize_t dp_aux_cmd_fifo_rx(struct dp_aux_private *aux,
> return i;
> }
>
> -static void dp_aux_native_handler(struct dp_aux_private *aux, u32 isr)
> +static irqreturn_t dp_aux_native_handler(struct dp_aux_private *aux, u32 isr)
> {
> - if (isr & DP_INTR_AUX_I2C_DONE)
> + irqreturn_t ret = IRQ_NONE;
> +
> + if (isr & DP_INTR_AUX_I2C_DONE) {
> aux->aux_error_num = DP_AUX_ERR_NONE;
> - else if (isr & DP_INTR_WRONG_ADDR)
> + ret = IRQ_HANDLED;
> + } else if (isr & DP_INTR_WRONG_ADDR) {
> aux->aux_error_num = DP_AUX_ERR_ADDR;
> - else if (isr & DP_INTR_TIMEOUT)
> + ret = IRQ_HANDLED;
> + } else if (isr & DP_INTR_TIMEOUT) {
> aux->aux_error_num = DP_AUX_ERR_TOUT;
> - if (isr & DP_INTR_NACK_DEFER)
> + ret = IRQ_HANDLED;
> + }
> +
> + if (isr & DP_INTR_NACK_DEFER) {
> aux->aux_error_num = DP_AUX_ERR_NACK;
> + ret = IRQ_HANDLED;
> + }
> +
> if (isr & DP_INTR_AUX_ERROR) {
> aux->aux_error_num = DP_AUX_ERR_PHY;
> dp_catalog_aux_clear_hw_interrupts(aux->catalog);
> + ret = IRQ_HANDLED;
> }
> +
> + return ret;
> }
>
> -static void dp_aux_i2c_handler(struct dp_aux_private *aux, u32 isr)
> +static irqreturn_t dp_aux_i2c_handler(struct dp_aux_private *aux, u32 isr)
> {
> + irqreturn_t ret = IRQ_NONE;
> +
> if (isr & DP_INTR_AUX_I2C_DONE) {
> if (isr & (DP_INTR_I2C_NACK | DP_INTR_I2C_DEFER))
> aux->aux_error_num = DP_AUX_ERR_NACK;
> else
> aux->aux_error_num = DP_AUX_ERR_NONE;
> - } else {
> - if (isr & DP_INTR_WRONG_ADDR)
> - aux->aux_error_num = DP_AUX_ERR_ADDR;
> - else if (isr & DP_INTR_TIMEOUT)
> - aux->aux_error_num = DP_AUX_ERR_TOUT;
> - if (isr & DP_INTR_NACK_DEFER)
> - aux->aux_error_num = DP_AUX_ERR_NACK_DEFER;
> - if (isr & DP_INTR_I2C_NACK)
> - aux->aux_error_num = DP_AUX_ERR_NACK;
> - if (isr & DP_INTR_I2C_DEFER)
> - aux->aux_error_num = DP_AUX_ERR_DEFER;
> - if (isr & DP_INTR_AUX_ERROR) {
> - aux->aux_error_num = DP_AUX_ERR_PHY;
> - dp_catalog_aux_clear_hw_interrupts(aux->catalog);
> - }
> +
> + return IRQ_HANDLED;
> + }
> +
> + if (isr & DP_INTR_WRONG_ADDR) {
> + aux->aux_error_num = DP_AUX_ERR_ADDR;
> + ret = IRQ_HANDLED;
> + } else if (isr & DP_INTR_TIMEOUT) {
> + aux->aux_error_num = DP_AUX_ERR_TOUT;
> + ret = IRQ_HANDLED;
> }
> +
> + if (isr & DP_INTR_NACK_DEFER) {
> + aux->aux_error_num = DP_AUX_ERR_NACK_DEFER;
> + ret = IRQ_HANDLED;
> + }
> +
> + if (isr & DP_INTR_I2C_NACK) {
> + aux->aux_error_num = DP_AUX_ERR_NACK;
> + ret = IRQ_HANDLED;
> + }
> +
> + if (isr & DP_INTR_I2C_DEFER) {
> + aux->aux_error_num = DP_AUX_ERR_DEFER;
> + ret = IRQ_HANDLED;
> + }
> +
> + if (isr & DP_INTR_AUX_ERROR) {
> + aux->aux_error_num = DP_AUX_ERR_PHY;
> + dp_catalog_aux_clear_hw_interrupts(aux->catalog);
> + ret = IRQ_HANDLED;
> + }
> +
> + return ret;
> }
>
> static void dp_aux_update_offset_and_segment(struct dp_aux_private *aux,
> @@ -413,6 +446,7 @@ void dp_aux_isr(struct drm_dp_aux *dp_aux)
> {
> u32 isr;
> struct dp_aux_private *aux;
> + irqreturn_t ret = IRQ_NONE;
No need to assign a value here. It will be overwritten in both of code
branches.
>
> if (!dp_aux) {
> DRM_ERROR("invalid input\n");
> @@ -423,15 +457,20 @@ void dp_aux_isr(struct drm_dp_aux *dp_aux)
>
> isr = dp_catalog_aux_get_irq(aux->catalog);
>
> + /* no interrupts pending, return immediately */
> + if (!isr)
> + return;
> +
A separate commit please.
> if (!aux->cmd_busy)
> return;
>
> if (aux->native)
> - dp_aux_native_handler(aux, isr);
> + ret = dp_aux_native_handler(aux, isr);
> else
> - dp_aux_i2c_handler(aux, isr);
> + ret = dp_aux_i2c_handler(aux, isr);
>
> - complete(&aux->comp);
> + if (ret == IRQ_HANDLED)
> + complete(&aux->comp);
Can you just move the complete() into the individual handling functions?
Then you won't have to return the error code from dp_aux_*_handler() at
all. You can check `isr' in that function and call complete if there was
any error.
Also could you please describe, why is it necessary to complete()
condition at all? Judging from your commit message the `if (!isr)
return;' part should be enough.
> }
>
> void dp_aux_reconfig(struct drm_dp_aux *dp_aux)
--
With best wishes
Dmitry
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