linux-kernel - Re: [PATCH 5/8] media: vidc: add Host Firmware Interface (HFI)

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Date:   Fri, 26 Aug 2016 17:21:10 +0300
From:   Stanimir Varbanov <stanimir.varbanov@...aro.org>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>
Cc:     Mauro Carvalho Chehab <mchehab@...nel.org>,
        Hans Verkuil <hverkuil@...all.nl>,
        Andy Gross <andy.gross@...aro.org>,
        Stephen Boyd <sboyd@...eaurora.org>,
        Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH 5/8] media: vidc: add Host Firmware Interface (HFI)

Hi Bjorn,

Thanks for the comments!

On 08/23/2016 06:25 AM, Bjorn Andersson wrote:
> On Mon 22 Aug 06:13 PDT 2016, Stanimir Varbanov wrote:
> 
>> This is the implementation of HFI. It is loaded with the
>> responsibility to comunicate with the firmware through an
>> interface commands and messages.
>>
>>  - hfi.c has interface functions used by the core, decoder
>> and encoder parts to comunicate with the firmware. For example
>> there are functions for session and core initialisation.
>>
> 
> I can't help feeling that the split between core.c and hfi.c is a
> remnant of a vidc driver supporting both HFI and pre-HFI with the same
> v4l code.
> 
> What do you think about merging vidc_core with hfi_core and vidc_inst
> with hfi_inst? Both seems to be in a 1:1 relationship.

OK, I can give it a try.

> 
>>  - hfi_cmds has packetization operations which preparing
>> packets to be send from host to firmware.
>>
>>  - hfi_msgs takes care of messages sent from firmware to the
>> host.
>>
> [..]
>> diff --git a/drivers/media/platform/qcom/vidc/hfi_cmds.c b/drivers/media/platform/qcom/vidc/hfi_cmds.c
> [..]
>> +
>> +static const struct hfi_packetization_ops hfi_default = {
>> +	.sys_init = pkt_sys_init,
>> +	.sys_pc_prep = pkt_sys_pc_prep,
>> +	.sys_idle_indicator = pkt_sys_idle_indicator,
>> +	.sys_power_control = pkt_sys_power_control,
>> +	.sys_set_resource = pkt_sys_set_resource,
>> +	.sys_release_resource = pkt_sys_unset_resource,
>> +	.sys_debug_config = pkt_sys_debug_config,
>> +	.sys_coverage_config = pkt_sys_coverage_config,
>> +	.sys_ping = pkt_sys_ping,
>> +	.sys_image_version = pkt_sys_image_version,
>> +	.ssr_cmd = pkt_ssr_cmd,
>> +	.session_init = pkt_session_init,
>> +	.session_cmd = pkt_session_cmd,
>> +	.session_set_buffers = pkt_session_set_buffers,
>> +	.session_release_buffers = pkt_session_release_buffers,
>> +	.session_etb_decoder = pkt_session_etb_decoder,
>> +	.session_etb_encoder = pkt_session_etb_encoder,
>> +	.session_ftb = pkt_session_ftb,
>> +	.session_parse_seq_header = pkt_session_parse_seq_header,
>> +	.session_get_seq_hdr = pkt_session_get_seq_hdr,
>> +	.session_flush = pkt_session_flush,
>> +	.session_get_property = pkt_session_get_property,
>> +	.session_set_property = pkt_session_set_property,
>> +};
>> +
>> +static const struct hfi_packetization_ops *get_3xx_ops(void)
>> +{
>> +	static struct hfi_packetization_ops hfi_3xx;
>> +
>> +	hfi_3xx = hfi_default;
>> +	hfi_3xx.session_set_property = pkt_session_set_property_3xx;
>> +
>> +	return &hfi_3xx;
>> +}
>> +
>> +const struct hfi_packetization_ops *
>> +hfi_get_pkt_ops(enum hfi_packetization_type type)
> 
> The only reasonable argument I can come up with for not just exposing
> these as global functions would be that there are 23 of them... Can we
> skip the jump table?

Of course we can, but what will be the benefit, increased readability ?
Let's keep it for now. Once the driver is merged some smarter guy could
came up with better solution ;)

> 
>> +{
>> +	switch (type) {
>> +	case HFI_PACKETIZATION_LEGACY:
>> +		return &hfi_default;
>> +	case HFI_PACKETIZATION_3XX:
>> +		return get_3xx_ops();
>> +	}
>> +
>> +	return NULL;
>> +}
> 
> Regards,
> Bjorn
> 

-- 
regards,
Stan