linux-kernel - Re: [v2] msm: disp: dpu1: add support to access hw irqs regs depending on revision

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Message-ID: <0101016e83ae22b5-7a05918b-c1c4-40f1-ae17-5dd36a003c36-000000@us-west-2.amazonses.com>
Date:   Tue, 19 Nov 2019 12:40:57 +0000
From:   dhar@...eaurora.org
To:     Stephen Boyd <swboyd@...omium.org>
Cc:     devicetree@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        freedreno@...ts.freedesktop.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org, robdclark@...il.com,
        seanpaul@...omium.org, hoegsberg@...omium.org,
        abhinavk@...eaurora.org, jsanka@...eaurora.org,
        chandanu@...eaurora.org, nganji@...eaurora.org
Subject: Re: [v2] msm: disp: dpu1: add support to access hw irqs regs
 depending on revision

On 2019-11-14 22:59, Stephen Boyd wrote:
> Quoting Shubhashree Dhar (2019-11-13 21:56:16)
>> Current code assumes that all the irqs registers offsets can be
>> accessed in all the hw revisions; this is not the case for some
>> targets that should not access some of the irq registers.
> 
> What happens if we read the irq registers that we "should not access"?
> Does the system reset? It would be easier to make those registers 
> return
> 0 when read indicating no interrupt and ignore writes so that 
> everything
> keeps working without having to skip registers.
> 
In some of the hw revisions, the whole hw block is absent and trying to 
access those
registers causes system panic(bus noc error).

>> This change adds the support to selectively remove the irqs that
>> are not supported in some of the hw revisions.
>> 
>> Change-Id: I6052b8237b703a1a9edd53893e04f7bd72223da1
> 
> Please remove these before sending upstream.
> 
>> Signed-off-by: Shubhashree Dhar <dhar@...eaurora.org>
>> ---
>>  drivers/gpu/drm/msm/disp/dpu1/dpu_hw_catalog.c    |  1 +
>>  drivers/gpu/drm/msm/disp/dpu1/dpu_hw_catalog.h    |  3 +++
>>  drivers/gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.c | 22 
>> +++++++++++++++++-----
>>  drivers/gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.h |  1 +
>>  4 files changed, 22 insertions(+), 5 deletions(-)
>> 
>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_catalog.h 
>> b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_catalog.h
>> index ec76b868..def8a3f 100644
>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_catalog.h
>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_catalog.h
>> @@ -646,6 +646,7 @@ struct dpu_perf_cfg {
>>   * @dma_formats        Supported formats for dma pipe
>>   * @cursor_formats     Supported formats for cursor pipe
>>   * @vig_formats        Supported formats for vig pipe
>> + * @mdss_irqs          Bitmap with the irqs supported by the target
> 
> Hmm pretty sure there needs to be a colon so that kernel-doc can match
> this but maybe I'm wrong.
> 
>>   */
>>  struct dpu_mdss_cfg {
>>         u32 hwversion;