Blame SOURCES/0158-efinet-Check-for-immediate-completition.patch

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From 763eff26748ca3d2ae8b178aef15da54a70527a5 Mon Sep 17 00:00:00 2001
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From: Martin Wilck <martin.wilck@ts.fujitsu.com>
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Date: Fri, 27 Mar 2015 14:27:56 +0100
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Subject: [PATCH 01/23] efinet: Check for immediate completition.
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This both speeds GRUB up and workarounds unexpected EFI behaviour.
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---
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 grub-core/net/drivers/efi/efinet.c | 16 ++++++++++++++--
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 1 file changed, 14 insertions(+), 2 deletions(-)
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diff --git a/grub-core/net/drivers/efi/efinet.c b/grub-core/net/drivers/efi/efinet.c
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index a6e4c79..78df215 100644
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--- a/grub-core/net/drivers/efi/efinet.c
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+++ b/grub-core/net/drivers/efi/efinet.c
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@@ -37,11 +37,12 @@ send_card_buffer (struct grub_net_card *dev,
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   grub_efi_status_t st;
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   grub_efi_simple_network_t *net = dev->efi_net;
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   grub_uint64_t limit_time = grub_get_time_ms () + 4000;
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+  void *txbuf;
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   if (dev->txbusy)
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     while (1)
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       {
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-	void *txbuf = NULL;
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+	txbuf = NULL;
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 	st = efi_call_3 (net->get_status, net, 0, &txbuf);
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 	if (st != GRUB_EFI_SUCCESS)
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 	  return grub_error (GRUB_ERR_IO,
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@@ -74,7 +75,18 @@ send_card_buffer (struct grub_net_card *dev,
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 		   dev->txbuf, NULL, NULL, NULL);
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   if (st != GRUB_EFI_SUCCESS)
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     return grub_error (GRUB_ERR_IO, N_("couldn't send network packet"));
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-  dev->txbusy = 1;
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+
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+  /*
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+     The card may have sent out the packet immediately - set txbusy
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+     to 0 in this case.
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+     Cases were observed where checking txbuf at the next call
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+     of send_card_buffer() is too late: 0 is returned in txbuf and
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+     we run in the GRUB_ERR_TIMEOUT case above.
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+     Perhaps a timeout in the FW has discarded the recycle buffer.
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+   */
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+  st = efi_call_3 (net->get_status, net, 0, &txbuf);
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+  dev->txbusy = !(st == GRUB_EFI_SUCCESS && txbuf == dev->txbuf);
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+
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   return GRUB_ERR_NONE;
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 }
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-- 
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2.4.3
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